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?
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?
Explanation
Initially, the total height of the 14 boys = Average height x Number of boys = 5.3 x 14 = 74.2 feet
After the new boy joined, the total height of the 15 boys = New average height x Total number of boys = 5.25 x 15 = 78.75 feet
Since the total height increased by the height of the new boy, we can set up the equation:
74.2 + New boy's height = 78.75
Subtract 74.2 from both sides:
New boy's height = 78.75 - 74.2
New boy's height = 4.55 feet
So, the new boy's height is 4.55 feet.