Question

A fisherman is weighing each of 50 fishes. Their mean weight worked out is 50 gm and a standard deviation of 2.5 gm. Later it was found that the measuring scale was misaligned and always under reported every fish weight by 2.5 gm. Find the mean and standard deviation of fishes.

(a) 52.5,2.5

(b) 30,5

(c) 50,5

(d) 48.5,2.5

The question was asked during an interview for a job.

My doubt stems from Statistics in chapter Statistics of Mathematics – Class 11

Answer 1

Correct answer is (a) 52.5,2.5

For explanation I would say: Since mean(X + b) = meanX + b and Var(X + b) = VarX, so we get correct mean as 50 + 2.5 = 52.5 gm and S.D. is 2.5 gm.