Question

Mean of the data x₁ , x₂, x₃, x₄ , x₅ is 15. If each observation is multiplied 3 then the mean becomes 

A) 5 

B) 45 

C) 18 

D) 12

Answer 1

Correct option is (B) 45

Given that mean of the data \(x_1, x_2, x_3 , x_4 , x_5\) is 15.

\(\therefore\) \(\frac{x_1+x_2+x_3+x_4+x_5}5=15\)

\(\Rightarrow\) \(x_1+x_2+x_3+x_4+x_5\) \(=15\times5=75\)   _________(1)

If each observation is multiplied by 3 then

Mean \(=\frac{3x_1+3x_2+3x_3+3x_4+3x_5}5\)

\(=\frac35(x_1+x_2+x_3+x_4+x_5)\)

\(=\frac35\times75=45\)

Answer 2

Correct option is B) 45