Question

The A.M. of 12 observations is 15. If an.
observation 20 is removed, what is the
arithmetic mean of the remaining
observations?
(A) 14.5 (B) 13 (C) 15 (D) 13.5​

Answer 1

ANSWER :

(A) 14.5 is the correct answer

EXPLANATION :

Let the sum of the 12 observations be s

Mean = sum of the observations / total no. of observations

15 = s/12

s=15×12

s=180

Now 20 is removed from the sum,

s-20 = 180-20 = 160

Now we have 11 observations and sum is 160

So, mean = 160/11

Mean = 14.5