SOLUTION: The average age of five boys is 15 years. A sixth boy joins them, making the average age 15 years and 6 months. What is the age of this sixth boy? Please reply as soon as possib

Algebra ->  Customizable Word Problem Solvers  -> Age -> SOLUTION: The average age of five boys is 15 years. A sixth boy joins them, making the average age 15 years and 6 months. What is the age of this sixth boy? Please reply as soon as possib      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 825853: The average age of five boys is 15 years. A sixth boy joins them, making the average age 15 years and 6 months. What is the age of this sixth boy?
Please reply as soon as possible because I am applying for Bergen Academies and I need help and I would really appreciate.
Thankyou!
My work:
15*5=75
75x=186
x=2.48
It is a impossible for the sixth boy to be 2.48 years old, therefore i find it difficult to complete this problem...

Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
15%2A5=75 is the sum of the ages of the first 5 boys.
When the sixth boy joins them, the sum of the ages of the 6 boys is
75%2Bx , and the average of the ages of the 6 boys is
%2875%2Bx%29%2F6
15 years and 6 months =15%261%2F2years=15.5years
So, %2875%2Bx%29%2F6=15.5 .

Solving:
%2875%2Bx%29%2F6=15.5
75%2Bx=15.5%2A6
75%2Bx=93
x=93-75
x=18

Think of it a different way to make it a mental math problem.
The sixth boy must be older than 15.
How much older?
His extra age (over 15) must be enough that divyied up over the 6 boys it would add 1%2F2 year to the average.
%281%2F2%29%2A6=3
SO that sixth boy is 3 years older than the average, and 15%2B3=highlight%2818%29 .