Question

The average age of4 children is 11 years of the ages of 3 children are 9 years 12 years and 10 years find the cage of the fourth child

Answer 1

The age of the fourth child is 13 years

Explanation:

Given:

1. The average age of 4 children is 11 years

2. The ages of 3 children are 9 years 12 years and 10 years

To find:

The age of Fourth children

Solution:

==> let the four children be a,b,c and d

==> $Average = \frac{a+b+c+d}{4}$

==> Average = 11 years

==> $11 = \frac{a+b+c+d}{4}$

==> 11×4 = a+b+c+d

==> 44 = a+b+c+d ==> 1

==> The age of 3 children are given

==> a = 9 years

==> b = 12 years

==> c = 10 years

==> Apply the values in the above equation 1

==>  44 = a+b+c+d

==> 44 = 9+12+10+d

==> 44 = 31+d

==> d = 44-31

==> d = 13 years

==> The age of the fourth child is 13 years