Question

the average age of 5 boys are 20 if average age of 4 of them is 16 find the age of 5th boy.plzz solve this problem

Answer 1

Hello Friend !

The solution is given below :

Let the four boys be B1 , B2 , B3 , B4 , and B4.

Then according to question average of four boys is 16

⇒ $\frac{B1 + B2 + B3 + B4 }{4} = 16$

⇒ B1 + B2 + B3 + B4 = 4 × 16 = 64                  ( Equation 1)

Also as given in the question average of five boys is 20

⇒ $\frac{B1 + B2 + B3 + B4 + B5 }{5} = 20$

⇒ B1 + B2 + B3 + B4 + B5 = 20 × 5 = 100

⇒ 64 + B5 = 100   (From equation 1)

⇒ B5 = 100 - 64 = 36 years .

This is the answer !

Hope this helps !!!