Question

The mean of 5 numbers is 50 and the mean of 4 of this numbers is 45. What is the fifth number

Answer 1

the fifth number is 70

Explanation:

mean (average) of first 5 numbers =50 , Then sum of this 5 numbers = 50*5 =250.

The mean of 4 numbers = 45 . Sum 4 numbers = 45*4 = 180

the fifth number is 250-180=70

(180 +70)/5=50 which is the mean