Question

The mean of eleven numbers is 5.5.when two more numbers are added, the mean of the numbers becomes 7. If the two numbers differ by 10, find the two numbers

Answer 1

The sum of the eleven numbers =5.5×11=60.5

Let the two numbers be a and b.

When adding the two numbers

(a+60.5+b)/13=7

a+b=91-60.5=30.5

Given a-b=10

By adding two equations

2a =40.5 , then a=20.25

by substituting in a-b=10

b=10.25

The two numbers are 20.25 &10.25