Given, The variance of 20 observations is 4.

To Find: Find the variance of resulting observations.

Explanation: Let Assume, x₁,x₂,x₃,…,x₁₅ be the given observations.

So, Variance (X) = 4 (Given)

X =

Now, Let u₁,u₂,…u₂₀ be the new observation,

When new observation increase by 9, then

U_i=x_i+9(for i=1,2,3…,20) ---(i)

Now,

Variance (U) =60

Hence, The variance of new observations is 60.