# A class had 14 boys with an average height of 5.3 feet. A new boy joined the class. Now the average of the 15 boys in the class was 5.25 feet. How tall was the new boy?

Feb 15, 2017

The height of the new boy is 4.55 feet

#### Explanation:

If there are 14 boys in the class and they average 5.3 feet, then the total height of the 14 boys is:

$14 \times 5.3 f e e t = 74.2 f e e t$

With a new boy admitted to the class there are now 15 boys and they average 5.25 feet, then the new total height of the 15 boys is:

$15 \times 5.25 f e e t = 78.75 f e e t$

To find the height of the new boy we subtract the old total height of all the boys (74.2 feet) from the new total height of all the boys (78.75 feet):

$78.75 f e e t - 74.2 f e e t = 4.55 f e e t$