Question

If Arithmetic Mean and coefficient of variation of x are 5 and 20 respectively. What is the variance
of (15-2x)?
(a) 16
(b) 2
(c) 4
(d) 32
​

Answer 1

Answer:

Its easy.

First find out the sd of X.

See,

Coefficient of variation = SD/Mean*100%

Assuming CoV is given in percentage,

=> SD = Mean*COV = 10*40% = 4

=> Var(X) = 16

Var(15–2X) = 4*Var(X) = 4*16 = 64

Note: If the CoV is not given in percentage please adjust accordingly