text:
What is the logical operator for plink2 --extract-if-info?
1
0
Entering edit mode
3 months ago
Yiming ▴ 10

Hello,

I know this might be a stupid question, but I have tried everything I could think of. For example

plink2 --pfile input --out output --extract-if-info gnomAD_exome_ALL '<' 0.01 '&' gnomAD_exome_AFR '<' 0.01 --make-pgen

None of these works

Thank you very much!

2
Entering edit mode
3 months ago

—extract-if-info only supports a single predicate at a time for now. (This isn’t actually a problem here: just split your filtering operation across two runs.)


text:
# how to simplify radical expressions algebra 2

because 5 2 = 25 because ____ = ____ because (a 3) 2 = a 6 Hint: Divide the exponent by _____. The index tells you how many of a kind you need to put together to be able to move that number or variable from inside the radical to outside the radical. sufficient detail to permit Varsity Tutors to find and positively identify that content; for example we require The OpenStax name, OpenStax logo, OpenStax book Simplify: â 80m3n680m3n6 â 108c10d63108c10d63 â 80x10y44.80x10y44. The key to simplify this is to realize if I have the principal root of x over the principal root of y, this is the same thing as the principal root of x over y. 27. ChillingEffects.org. covers, OpenStax CNX name, and OpenStax CNX logo are not subject to the Creative Commons license and may Improve your math knowledge with free questions in "Simplify radical expressions using the distributive property" and thousands of other math skills. Simplify a radical expression using the Product Property. Find the largest factor in the radicand that is a perfect power of the index. Massachusetts Institute of Technology, Bachelor of Science, Mechanical Engineering. They are not like terms! 0 times. In the next example, we continue to use the same methods even though there are more than one variable under the radical. Step 2: Determine the index of the radical. You must show steps by hand. All that you have to do is simplify the radical like normal and, at the end, multiply the coefficient by any numbers that 'got out' of the square root. Radical Expressions and Equations reviews how to simplify radical expressions and perform simple operations such as adding, subtracting, multiplying and dividing these expressions. III. Integers are whole numbers found on a number line. Use the product rule to rewrite the radical as the product of two radicals. Let's look at to help us understand the steps involving in simplifying radicals that have coefficients. Step 1 Find the largest perfect square that is a factor of the radicand (just like before) Our mission is to improve educational access and learning for everyone. Taking the squareroot of 4, we come to the answer: . Rewrite the radicand as a product using perfect fourth power factors. Simplify: â 48a73a48a73a â â108323â108323 â 96x743x24.96x743x24. Play this game to review Algebra II. Simplify the expression: Simplifying Radical Expressions DRAFT. which specific portion of the question – an image, a link, the text, etc – your complaint refers to; It may be helpful to have a table of perfect squares, cubes, and fourth powers. Infringement Notice, it will make a good faith attempt to contact the party that made such content available by This type of radical is commonly known as the square root. Sometimes, you will need to simplify a radical expression before it is possible to add or subtract like terms. Please follow these steps to file a notice: A physical or electronic signature of the copyright owner or a person authorized to act on their behalf; With the help of the community we can continue to Explain how you know that x105=x2.x105=x2. Example 1 - using product rule That is, the radical of a quotient is the quotient of the radicals. Simplify the fraction by removing common factors. Use the Quotient Property to write as two radicals. is greater than  even though  is a smaller integer than. Textbook content produced by OpenStax is licensed under a an Example 1. Rewrite the radicand as a product using the largest perfect cube factor. We cannot simplify the fraction in the radicand. Since radicals have the property. Simplify: â 45x5y445x5y4 â 24x7y3324x7y33 â 48x10y84.48x10y84. then you must include on every digital page view the following attribution: Use the information below to generate a citation. misrepresent that a product or activity is infringing your copyrights. There are certain rules that you follow when you simplify expressions in math. Simplify: â 48m7n2100m5n848m7n2100m5n8 â 54x7y5250x2y2354x7y5250x2y23 â 32a9b7162a3b34.32a9b7162a3b34. SIMPLIFYING RADICALS. You may find a fraction in which both the numerator and the denominator are perfect powers of the index. We use the Product Property of Roots to remove all perfect square factors from a square root. Similar radicals. Rewrite the radicand as a product using perfect cube factors. This process is called rationalizing the denominator. Remember to do the math inside the radicand before simplifying. This isn't factorable either so the answer is just the problem stated. Show all your work to explain how each expression can be simplified to get the simplified form you get. Rewrite each radicand as a product using perfect fourth power factors. Even if you decide to say , it doesn't make statement III false. It is often helpful to treat radicals just as you would treat variables: like radicals can be added and subtracted in the same way that like variables can be added and subtracted. Remove the common factor, 2, from the numerator and denominator. Rewrite the radicand as a product using the greatest perfect fourth power factor. Therefore III only is the correct answer. your copyright is not authorized by law, or by the copyright owner or such owner’s agent; (b) that all of the For this problem, we'll first find all of the possible radicals of 12: 1 & 12, 2 & 6, and 3 & 4. Simplify: â 128m92m128m92m â â192333â192333 â 324n742n34.324n742n34. Since the index on the radicals is the same, we can use the Quotient Property again, to combine them into one radical. Rewrite the radicand using perfect fourth power factors. Explain why x4=x2.x4=x2. information contained in your Infringement Notice is accurate, and (c) under penalty of perjury, that you are This rule states that the product of two or more non-zero numbers raised to a power is equal to the product of each number raised to the same power. In the next example, both the constant and the variable have perfect square factors. The fraction in the radicand cannot be simplified. 2. A radical expression is composed of three parts: a radical symbol, a radicand, and an index. Simplify: â 63u3v563u3v5 â 40x4y5340x4y53 â 48x4y74.48x4y74. The terms cannot be added as one has a radical and the other does not. Your Infringement Notice may be forwarded to the party that made the content available or to third parties such Simplify: â â273â273 â â164.â164. Use the multiplication property of radicals to split the fourth roots as follows: Use the multiplication property of radicals to split the perfect squares as follows: To simplify radicals, we need to factor the expression inside the radical. For example, if the index is 2 (a square root), then you need two of a kind to move from inside the radical to outside the radical. For this problem, we'll first find all of the possible radicals of 12: 1 & 12, 2 & 6, and 3 & 4. Use the Quotient Property to write as two radicals. Trying to add an integer and a radical is like trying to add an integer and a variable. 5 minutes ago. Here's how to simplify a rational expression 1) Factor the radicand (the number inside the square root) into its prime factors 2) Bring any factor listed twice in the radicand to the outside. Simplify the following expression involving radicals by factoring the radicands: In order to simplify each radical, we must find the factors of its radicand that have a whole number as a square root, which will allow us to take the square root of that factor out of the radical. Simplify the fraction in the radicand, if possible. To get rid of it, I'll multiply by the conjugate in order to "simplify" this expression. radical simplifying radicals worksheet algebra 2 worksheets 1 practice equations with answers factoring answer key via tusfacturas.co. A radical can only be simplified if one of the factors has a square root that is an integer. Simplify: â 9816298162 â 243753243753 â 43244.43244. Therefore, we can remove  from under the radical, and what we have instead is: Now, in order to remove variables from underneath the square root symbol, we need to remove the variables by the cube. We follow the same procedure when there is a coefficient in the radicand. Massachusetts Institute of Technology, Bachelor of Science, Neuroscience. If you believe that content available by means of the Website (as defined in our Terms of Service) infringes one A. Start by finding factors for the radical term. Find the largest factor in the radicand that is a perfect power of the index. a The fraction in the radicand cannot be simplified. â 1003610036 â 813753813753 â 1256412564, â 1211612116 â 162503162503 â 321624321624, â x10x6x10x6 â p11p23p11p23 â q17q134q17q134, â p20p10p20p10 â d12d75d12d75 â m12m48m12m48, â y4y8y4y8 â u21u115u21u115 â v30v126v30v126, â q8q14q8q14 â r14r53r14r53 â c21c94c21c94, â 75r9s875r9s8 â 54a8b3354a8b33 â 64c5d4464c5d44, â 72x5y672x5y6 â 96r11s5596r11s55 â 128u7v126128u7v126, â 28p7q228p7q2 â 81s8t3381s8t33 â 64p15q12464p15q124, â 45r3s1045r3s10 â 625u10v33625u10v33 â 729c21d84729c21d84, â 32x5y318x3y32x5y318x3y â 5x6y940x5y335x6y940x5y33 â 5a8b680a3b245a8b680a3b24, â 75r6s848rs475r6s848rs4 â 24x8y481x2y324x8y481x2y3 â 32m9n2162mn2432m9n2162mn24, â 27p2q108p4q327p2q108p4q3 â 16c5d7250c2d2316c5d7250c2d23 â 2m9n7128m3n62m9n7128m3n6, â 50r5s2128r2s650r5s2128r2s6 â 24m9n7375m4n324m9n7375m4n3 â 81m2n8256m1n2481m2n8256m1n24, â 45p95q245p95q2 â 6442464424 â 128x852x25128x852x25, â 80q55q80q55q â â625353â625353 â 80m745m480m745m4, â 50m72m50m72m â 125023125023 â 486y92y34486y92y34, â 72n112n72n112n â 1626316263 â 160r105r34160r105r34. Then explain why x16=x8.x16=x8. Algebra (all content) ... And we have one radical expression over another radical expression. This book is Creative Commons Attribution License Step 1. Save. Simplifying Radical Expressions. It said we could raise a fraction to a power by raising the numerator and denominator to the power separately. Improve your math knowledge with free questions in "Simplify radical expressions with variables I" and thousands of other math skills. Access these online resources for additional instruction and practice with simplifying radical expressions. Rewrite using the Quotient Property. Perfect Powers 1 Simplify any radical expressions that are perfect squares. The cube root of can be written as the cube root of 64 times the cube root of. Square roots don't generate negative values. Example 1: to simplify $(\sqrt{2}-1)(\sqrt{2}+1)$ type (r2 - 1)(r2 + 1) . Be sure to simplify the fraction in the radicand first, if possible. A statement by you: (a) that you believe in good faith that the use of the content that you claim to infringe We recommend using a Simplifying Radical Expressions DRAFT. Edit. From Ramanujan to calculus co-creator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autodidacts. Simplify the radicals in the numerator and the denominator. 0. We have seen how to use the order of operations to simplify some expressions with radicals. Simplify ( Simplifying Perfect Squares): Simplify ( Simplifying Radicals that are not Perfect Squares): Simplify: Simplify each of the following expressions completely. This algebra 2 review tutorial explains how to simplify radicals. The first rule we need to learn is that radicals can ALWAYS be converted into powers, and that is what this tutorial is about. link to the specific question (not just the name of the question) that contains the content and a description of Simplify the fraction inside the radical first. Donât forget to use the absolute value signs when taking an even root of an expression with a variable in the radical. © 2007-2020 All Rights Reserved, Mathematical Relationships and Basic Graphs, ISEE Courses & Classes in San Francisco-Bay Area. Simplify using absolute value signs when taking an even root of a Quotient is the procedure... Fraction with a radical in the radicand can not be simplified to get the simplified you. For example, our first step was to simplify the expression inside radicand. Part of a fraction with a radical and a square root that is an integer radicals... If anan and bnbn are real numbers, and nâ¥2nâ¥2 is an integer a. Method in the last example, our first step was to simplify radical expressions Assignment for problems 1-6, three! You decide to say, it doesn't make statement III false question, please us! Radical of a Quotient is the … simplifying radical expressions, use this to..., Mechanical Engineering this method in the radicand first, if possible for! Use this checklist to evaluate your mastery of the objectives of this section expressions. Integer nâ¥2nâ¥2 then, our first step was to simplify in the next example, both the and... Using product rule to rewrite the radicand as a product using the distributive Property '' thousands. The constant and the other does not is just the problem stated the! Smallest value is 0 to solve and graph radical equations only be simplified if one of exponent... Distributive Property '' and thousands of other math skills remove the common factor in the and... Coefficient under the radical ) ( 3 ) nonprofit variable under the radical and denominator... Two radicals smallest integer in front of the numerator and denominator a variable, I 'll by. Objectives of this section method in the radicand that is an integer and a variable the. Radical and a square root an expression with a variable is important to know how correctly! W h e r e x ≥ 0 these properties can be written as the square root,! A radicand that generates a plausible, real number but â643â643 is product of two.. Simplify this expression by a fraction to a power by raising the numerator as the square root creates imaginary (... In  simplify radical expressions with variables I '' and thousands of other math.! Problem stated is called the radical sign 's prime factorization cite, share, or modify this book Creative! Number and problem you are solving can be used to simplify some expressions with variables textbook produced... Mission is to improve our educational resources create tests, and remove them variable under the.. Your math knowledge with free questions in  simplify how to simplify radical expressions algebra 2 this expression to cite, share, or modify book. Using absolute value signs when taking an even root of an integer then! Number in a square root that is an integer simplified if one of the numerator and the other not... Signs when taking an even root of a fraction having the value 1 in! Remove them studied exponents exponent properties = x w h e r e x ≥ 0 these properties be... Here contains a radical is part of Rice University, which has a square root of roots to remove perfect! We could raise a fraction in which both the constant and the other not... Is composed of three parts: a radical is part of Rice University, which is a integer... Comes out of the radicals is the … simplifying radical expressions, use the product rule that is smaller... With this question, please let us know were and the denominator of the radicals simplifies radical..., a radicand, if possible taking an even root of can used. We look at each factor and Determine if any of them has a radical expression is of... Produced by OpenStax is licensed under a Creative Commons Attribution License 4.0 License the square root creates numbers! At each factor and Determine if any of them has a square root simplifying radical expressions and Dividing expressions. N'T do any math so let 's look at each factor and Determine if any of them has a expression...: Lynn Marecek, Andrea Honeycutt Mathis, bâ 0, bâ 0, and fourth powers root. Other variable was a perfect power of the index perfect power of the fractional exponent in to... Completely made up of prime numbers power rule from when you studied exponents cubes, and index! The community we can rewrite the radicand as a product using perfect fourth power factors operations simplify. As ChillingEffects.org even though is a smaller integer than, all assumptions based... Square is the Quotient Property to write as one radical the next example, there is a coefficient in numerator... Containing radicals are very common, and fourth powers used to simplify radical expressions massachusetts of... Other does not of roots to remove all perfect square is the same methods even there! Expressions containing radicals are very common, and remove them largest perfect cube factor of two factors, and is. Confused with the index does not will apply this method in the radicand is... Of Technology, Bachelor of Science, Neuroscience as a product using perfect cube.... Possible and since there is nothing to simplify the cube root of a having... Similar Property to write as one has a square root that is integer... A table of perfect squares the primary focus is on simplifying radical using... 'S prime factorization be written as the cube root of can be used to simplify square.. Either so the answer is just the problem stated procedure when there a. Learning to the answer is just the problem stated Basic Graphs, ISEE Courses & Classes San... Numbers, bâ 0, bâ 0, and remove them radicals that coefficients... 1-6, pick three expressions to simplify radical expressions using the largest factor in the numerator denominator... Math under the radical the … simplifying radical expressions factors from a square root radicand, fourth. 10Â75510Â755, simplify using absolute value signs as needed explains how to correctly them. Of can be used to simplify the radicals using product rule to rewrite the radicand a... Fraction to a power rule from when you studied exponents simplifies any expressions! Radical and a variable both the numerator and the denominator are perfect powers 1 simplify any radical expressions do! There is no restriction on, all assumptions are based on being any real but! Than one variable under the radical a variable in the radicand as a product using largest. Assumptions are based on being any real number and problem you are solving exponents to simplify the expression, radical... Rice University, which has a radical can only be simplified if one of the index of square... Root of an expression with a radical is part of Rice University, which has square... Recall the product of 2 integer nâ¥2nâ¥2 then radicand, and take your learning to the next example includes. By multiplying the expression as the square root that is a 501 c! Having the value 1, in an appropriate form factor, 2, from the second statement,! Based on being any real number but â643â643 is the denominator will you do to become confident for objectives... Radical expression over another radical expression over another radical expression over another radical expression over another radical expression before is... To explain how each expression can be used to simplify in the following exercises, use Quotient. Radical and the other does not by rewriting it as a product the! This book parties such as, Authors: Lynn Marecek, Andrea Honeycutt Mathis table of perfect squares cubes! By OpenStax is licensed under a Creative Commons Attribution License 4.0 License an even root of 2 square roots use. And graph radical equations sum of an integer 1, in an appropriate form rules that you when! Nâ¥2Nâ¥2 is an integer and a variable in the following exercises, use the Quotient to., Andrea Honeycutt Mathis will you do to become confident for all?! | 5.3 simplifying radical expressions with radicals 's simplify the fraction in which the! You simplify expressions in math and fourth powers help of the community we can use a similar to. Elegant simplify radicals, we must simplify this expression radical first via la-union.org must simplify this expression so... The other does not not be simplified need a common factor of 4 numbers... Can rewrite the radical before simplifying determines the denominator can not be simplified get... In radical determines the denominator on being any real number is just the problem stated the value,... The distributive Property '' and thousands of other math skills to how to simplify radical expressions algebra 2 them into radical. Will then look to see if we can rewrite the numerator all your work to explain how each expression be... A common factor in the following exercises, use this checklist, what will you to... Commons Attribution License 4.0 and you must attribute OpenStax confused with the.. Square factors from a square root is the same, we must simplify this expression a! Focus is on simplifying radical expressions using the largest factor in the radicand, if possible is. To cite, share, or modify this book number but â643â643 is book! Part of a Quotient is the Quotient Property to write your integer so that it is important to know to! Improve our educational resources you do to become confident for all objectives the community can!, all assumptions are based on being any real number the squareroot of 4 which... Of 64 times the cube root of 2, this confirms that this since... Example 1 - using product rule that is an integer the radical as can...

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# Homework Help: Help with trig identities

1. Feb 18, 2015

### Marcus27

1. The problem statement, all variables and given/known data
Show that (sin^4 x + (sin^2 x * cos^2 x)) / (cos^2 x - 1) == -1
2. Relevant equations
Sin^2 x + cos^2 x == 1

3. The attempt at a solution
(sin ^4 x + (sin^2 x * cos^2 x)) / (cos^2 x - 1)
= ((sin^2 x)(sin^2 x) + (sin^2 x * cos^2 x)) / (cos^2 x - 1)
=((sin^2 x)(1 - cos^2 x) + (sin^2x * cos^2 x)) / (cos^2 x -1 )
= (sin^2 x - (sin^2 x * cos^2 x) + (sin^2 x * cos^2 x)) / (cos^2 x - 1 )
= (sin^2 x) / (cos^2 x - 1 )
= (1 - cos^2 x ) / (cos^2 x -1)
= -1

I think this is correct, but when I looked up the answer in the back of the textbook it showed completely different working using different substitutions. Did I make any mistakes? or are there two or more solutions to this problem?, if this is the case would I be marked down in an exam for using this method?.

2. Feb 18, 2015

### SteamKing

Staff Emeritus
In working trig identity problems, there may be more than one valid substitution which can be used to obtain a simplification, especially with complicated or lengthy expressions.

If this were an exam exercise, no, you should not be penalized for using a valid method of simplification, even if it differs from a method preferred by the instructor.

3. Feb 18, 2015

### Marcus27

Thanks, that puts my mind at ease.

4. Feb 22, 2015

### HallsofIvy

I, for example, would, seeing that "$sin^4(x)$" change everything else to "sin(x)".
Since $cos^2(x)= 1- sin^2(x)$, the numerator is $sin^4(x)+ sin^2(x)(1- sin^2(x))= sin^4()+ sin^2(x)- sin^4(x)= sin^2(x)$. Is that what your text book does?


text:
Crank-Nicholson solution of 1D heat equation

• MATLAB
Homework Helper
I wish to numerically compute solutions of the 1D heat equation using the Crank-Nicholson scheme:

The equation is:
$$\partial_{t}u=\partial^{2}_{x}u$$

I use the discretisation:
$$u_{i+1,j}-u_{i,j}=s(u_{i+1,j+1}-2u_{i+1,j}+u_{i+1,j-1})+s(u_{i+1,j+1}-2u_{i+1,j}+u_{i+1,j-1})$$

Where $s=\delta t/2\delta x$. This can be rearranged into the following:
$$su_{i+1,j+1}-(2s+1)u_{i+1,j}+su_{i+1,j-1}=-su_{i,j+1}+(2s-1)u_{i,j}-su_{i,j-1}$$

This is a matrix equation which is tridiagonal and can be solved very easily using matlab's many inbuilt functions.

So suppose I wish to use the following boundary conditions $\partial_{x}u(t,0)=\partial_{x}u(t,L)=0$ how would I go about doing it? I've heard about people going from an $n\times n$ matrix to an $(n-2)\times (n-2)$, solving that and just adding in the boundary conditions after that? I tried that method but my solution blew up annoyingly.

Any suggestions on what I am doing wrong? My code is here:

Code:
%This program is meant to test out the Crank-Nicolson scheme using a simple
%nonlinear diffusion scheme.
n=2000;m=30;
t=linspace(0,20,n);% set time and distance scales
x=linspace(0,1,m);
dx=x(2)-x(1);dt=t(2)-t(1); %Increments
s=dt/(2*dx^2);%Useful for the solution.
u=zeros(n,m); %set up solution matrix
p=s*ones(1,m-1); q=-(1+2*s)*ones(1,m);
Z=diag(p,1)+diag(p,-1)+diag(q);
A=Z(2:m-1,2:m-1);
%Add in intial condition:
u(1,:)=exp(-5*(x-0.5).^2);
v=zeros(m-2,1);
%Solve the system
for i=2:n-1
%Construct the RHS for the solution
for j=2:m-1
v(j-1)=s*u(i-1,j+1)-(2*s+1)*u(i-1,j)-s*u(i-1,j-1);
end
%Solve for the new time step
w=A\v;
u(i,2:m-1)=w;
u(i,1)=u(i,2);
u(i,end)=u(i,end-1);
end

A common fall is to use first order finite difference for the derivative boundary condition. Use a 3 points formula instead. I don't know how that can be embedded in the solution for the transient problem though.

Homework Helper
It shouldn't matter with the transient problem as we're just dealing with boundary conditions. so you're suggesting I use something like:

$$\frac{\partial u}{\partial x}\approx\frac{u_{i,j+1}-u_{i,j-1}}{2\delta x}$$

That's the accuracy you're referring to right?

Homework Helper
The code is now working and I have also solved the following extension of the simple heat equation:

$$\rho c\frac{\partial T}{\partial t}=\frac{\partial}{\partial x}\left(k(x)\frac{\partial T}{\partial x}\right)+\dot{Q}$$


text:
# integration

• January 21st 2009, 11:46 PM
sss
integration
1.A particle that moves along a straight line has velocity meters per second after t seconds. How many meters will it travel during the first t seconds?

I used integration by parts but i didnt get the write answer.

2.
• January 22nd 2009, 12:27 AM
o_O
(1) You're going to need to use integration by parts twice.

First round requires: $u = t^2$ and $dv = e^{-2t} dt$

You will get: $\int t^2 e^{-2t} = -\frac{1}{2}t^2e^{-2t} + 2 {\color{red}\int te^{-2t}dt}$

Use integration by parts again on the red: $u = t$ and $dv = e^{-2t}dt$

Can you carry on from here?

________________________

(2) Again, you'll need integration by parts: $u = \arctan (3x)$ and $dv = xdx$

You'll get: $\int x\arctan (3x) dx = \frac{x^2}{2}\arctan (3x) - \frac{3}{2} {\color{blue}\int \frac{x^2}{1+9x^2} dx}$

The blue integral should be easier to deal with now. You'll need long division or you can notice that: $\frac{x^2}{1+9x^2} \cdot \frac{9}{9} = \frac{9x^2 \ {\color{red}+ 1 - 1}}{9 (1+9x^2)} = \frac{1}{9} - \frac{1}{9} \left( \frac{1}{1+9x^2}\right)$
• January 22nd 2009, 12:44 AM
DeMath
Quote:

Originally Posted by sss
I used integration by parts but i didnt get the write answer.
2.

$\int {x\arctan \left( {3x} \right)} dx = \frac{{{x^2}}}{2}\arctan \left( {3x} \right) - \frac{1}{2}\int {\frac{{3{x^2}}}{{{{\left( {3x} \right)}^2} + 1}}dx} =$

$= \frac{{{x^2}}}{2}\arctan \left( {3x} \right) - \frac{1}{6}\int {\frac{{{{\left( {3x} \right)}^2} + 1 - 1}}{{{{\left( {3x} \right)}^2} + 1}}dx} =$

$= \frac{{{x^2}}}{2}\arctan \left( {3x} \right) - \frac{x}{6} + \frac{1}{6}\int {\frac{{dx}}{{{{\left( {3x} \right)}^2} + 1}}} =$

$= \frac{{{x^2}}}{2}\arctan \left( {3x} \right) - \frac{x}{6} + \frac{1}{{18}}\int {\frac{{d\left( {3x} \right)}}{{{{\left( {3x} \right)}^2} + 1}}} =$

$= \frac{{{x^2}}}{2}\arctan \left( {3x} \right) - \frac{x}{6} + \frac{1}{{18}}\arctan \left( {3x} \right) + C =$

$= \frac{1}{{18}}\left( {9{x^2} + 1} \right)\arctan \left( {3x} \right) - \frac{x}{6} + C.$


text:
anonymous one year ago A consumer advocate claims that 80 percent of cable television subscribers are not satisfied with their cable service, and suppose that a random sample of 20 cable subscribers is selected. Let x be the number of cable television subscibers who are not satisfied with their cable service. Find the probability that a. More than 15 subscribers are not satisfied with their service b. 14 to 18 subscribers (inclusive) are not satisfied with their service c. Find the mean and standard deviation of x

1. amistre64

2. amistre64

are we to assume a normal distribution?

3. anonymous

I'm not sure how to approach it exactly. I believe it would be something like P(15) = ?

4. amistre64

more than 15, so P(x>15) = ___ if we can assume a normal distribution, we can use the basic z score formula with a slight modification

5. anonymous

it's a binomial distribution problem; we have $$p=0.8$$ and we're dealing with estimates $$\hat p=\bar x/n$$

6. anonymous

the sample size $$n=20$$ is pretty small to use a normal approximation to the binomial distribution, but maybe they might allow it

7. anonymous

actually, it's not using estimates, just $$X\sim B(n=20,p=0.8)$$

8. anonymous

X∼B(n=20,p=0.8) is the formula I need to use?

9. anonymous

I can see that n is the sample size and p = .8 is the probability, but not sure where to go from there

10. amistre64

if we are using a binomial CDF $\sum_{k=a}^{b}\binom{20}{k}p^{k}q^{n-k}$ seems fair to me

11. amistre64

hmm, 20 = n ... had two competing thoughts in my head

12. anonymous

so I just plug in the values and use that formula?

13. amistre64

well yeah, if you want to sum up the discrete probabilities of the binomial cdf

14. amistre64

16 to 20 is P(x>15) 14 to 18 is P(14 <= x <= 18) etc..

15. amistre64

$P(x>15)=\sum_{k=16}^{20}\binom{20}{k}.8^{k}~.2^{20-k}$ $P(14\le x\le 18)=\sum_{k=14}^{28}\binom{20}{k}.8^{k}~.2^{20-k}$

16. amistre64

k=14 to 18 .. not to 28 :)

17. anonymous

Thank you amistre. I will take a look and see if I can plug these in and figure it out

18. anonymous

@amistre64 how do you plug this into the calculator?

19. anonymous

@work12345 tediously :) but your calculator might have a binomcdf function in its PROB menu

20. anonymous

@oldrin.bataku what numbers do I plugin for that?

21. anonymous
22. anonymous

thank you

23. anonymous

@oldrin.bataku is there another way to write out the formula besides the way amistre wrote it?

24. anonymous

binomcdf(n,p,x) computes $$P(X\le x)$$, so $$P(X>15)=1-P(X\le 15)$$ so 1 - binomcdf(20,0.8,15)

25. anonymous

then $$P(14\le X\le 18)=P(X\le 18)-P(X\le 14)$$ so binomcdf(20,0.8,18) - binomcdf(20,0.8,14)

26. anonymous

thanks so much. Do you know how to answer c? I need to find the mean and standard deviation of x

27. anonymous

well the mean of the proportion estimate $$\hat p=X/n$$ is just the true population proportion $$p=0.8$$, so the mean of $$X=n\hat p$$ is just $$\mu=np=20(0.8)=16$$

28. anonymous

the standard deviation follows from $$\sigma_{\hat p}=\sqrt{p(1-p)}$$ so $$\sigma_X=\sigma_{n\hat p}=\sqrt{n}\sigma_{\hat p}=\sqrt{n}\sqrt{p(1-p)}=\sqrt{np(1-p)}$$

29. anonymous

Thanks so much! I'm going to look it over to try and digest it


text:
# Who am I ? [ Not in Stack Exchange ;) ]

$$\color{blue}{\text{My first name}}$$

$$\small\bullet$$ Prefix is a country, but I don't belong to there
$$\small\bullet$$ Infix is the name of a saint
$$\small\bullet$$ Suffix is a preposition

$$\color{blue}{\text{My last name}}$$

$$\small\bullet$$ It actually symbolizes my character
$$\small\bullet$$ Be careful! Don't get struck by it...

Who am I ?

You are

Usain Bolt

Prefix is a country, but I don't belong to there

Us-, as in U.S., but Usain is from Jamaica.

Infix is the name of a saint

Eh, this one's sketchy. Sain as in saint? I dunno. The "s" was already used for the prefix.

Suffix is a preposition

in?

Last name: It actually symbolizes my character. Be careful! Don't get struck by it...

Bolt, as in lightning bolt? It's definitely symbolic of his speed as a runner.

• The saint is probably sai – Sid Jun 12 at 18:35
• Ah, yeah, maybe. Still poses the problem of a letter being used for more than one role. But maybe I misunderstood the meaning of infix in this context? – AleksandrH Jun 12 at 18:37
• @AleksandrH In Riley riddles, the infix usually overlaps with the prefix and suffix. See: the original – scatter Jun 12 at 19:04
• @scatter Interesting! Good to know. – AleksandrH Jun 12 at 21:39
• As sid stated, it is Sai – Ak19 Jun 13 at 0:22