The arithmetic mean of 10 number is-7. If 5 is added to every number, then the new Arithmetic mean is

Given that, arithmetic mean of 10 numbers = -7

We know, total number of observations, n = 10

Then, mean is given by

⇒

⇒ Sum of all observations = 10 × -7 = -70

According to question, if 5 is added to every 10 number then,

New sum of all observations = Old sum + (5 × 10)

⇒ New sum = -70 + 50 = -20

⇒

⇒ New mean = -2

Thus, option (A) is correct.