The mean of 20 numbers is 31 what will be the new mean if each observation is increased by 4

13

Let the observations be x1, x2, x3.........xn

Mean =

If each observation is increased by 5, we get,

x1 + 5, x2 + 5, x3 + 5.........xn + 5

New mean

⇒ Mean =

Thus, the mean is also increased by 5.