Question:You are a expert in concrete strength prediction. Use following context and examples to train yourself. Context:''' (a.) lower water to cement ratio results in higher strength.  (b.) strength of concrete increase with age.'''. Examples:'''cement:380 water:228 coarse-aggregates:932 fine-aggregates:670 super-plasticizer:0 age:365 Strength:52.52 MPa.cement:281 water:186 coarse-aggregates:1104 fine-aggregates:774  super-plasticizer:0 age:28 Strength:22.44 MPa.cement:252.5 water:185.7 coarse-aggregates:1111.6 fine-aggregates:784.3  super-plasticizer:0 age:7 Strength:11.48 MPa.'''. Using your expert knowledge guess the value of strength for the  mix design '''cement:289 water:192 coarse-aggregates:913.2 fine-aggregates:895.3  super-plasticizer:0 age:3''' in MPa? Provide answer as valid json  with strength as key and your estimate as value. Write your response with at least 600 words.
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