Answer:
21, 144, 12
Explanation:
Given that a sample of 30 distance scores measured in yards has a mean of 7, a variance of 16, and a standard deviation of 4.
Let X be the distance in yard.
i.e. each entry of x is multiplied by 3.
New mean variance std devition would be
E(3x) =

Var (3x) =

Std dev (3x) =

Thus we find mean and std devition get multiplied by 3, variance is multiplied by 9