Question

Mean and standard deviations of 10 observations are 20 and 2 respectively. If p (p ≠ 0) is multiplied to each observation and then q (q ≠ 0) is subtracted then new mean and standard deviation becomes half of original value . Then find q

(1) –10 

(2) –20 

(3) –5 

(4) 10

Answer 1

Answer is (2) - 20

If each observation is multiplied with p & then q is subtracted