Question

The mean of ten numbers is 55.If one numbers is excluded, their mean becomes 50.Find the excluded number.

Answer 1

the excluded Number should be 5.0

Answer 2

Answer: 100 is the number which is excluded to make the mean to be 50.

Given:

The mean of 10 numbers = 55

If one number is excluded, their mean becomes 50.

Solution:

Let the number which is excluded is denoted as x

The nine numbers can be denoted as y

Given$\frac{x+y}{10}$ =55

x + y = 550 … (1)

y = 550 – x … (2)

Given $\frac{y}{9}$ =50

y = 450 … (3)

Substitute (3) in (2),

y = 550 – x

x = 550 – 450

x = 100