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?

1 Answer
smendyka
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 xx 5.3 feet = 74.2 feet#

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 xx 5.25 feet = 78.75 feet#

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 feet - 74.2 feet = 4.55 feet#

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