Question

A batsman played 17 innings during a season and he was not out. The score of 85 improves his average by 3 runs in the 17th innings. His average score after 16th innings is

Answer 1

let a = his average after the 17th inning

then

(a-3) = his average before the 17th

:

a = %28%2816%28a-3%29%2B85%29%29%2F17

multiply both sides by 17

17a = 16(a-3) + 85

17a = 16a - 48 + 85

17a - 16a = 37

a = 37 his average after 17 innings