Five-eighths of the students in a class got A's and B's.

[mommy99]

My neice has a math question that she needs help with.

Five-eighths of the students in a class got A's and B's. Four times as many students got A's as got B's. What percentage of the students got A's?

I must be getting old, because I'm having to luck in figuring this out. Thank you for your help!

 

[pka]

Suppose that there are N students in the class. Then
\(\displaystyle \L \begin{array}{l}
A + B = \frac{5}{8}N\quad \& \quad A = 4B \\
4B + B = \frac{5}{8}N\quad \Rightarrow \quad 5B = \frac{5}{8}N\quad \Rightarrow \quad B = \frac{1}{8}N \\
A = \frac{1}{2}N \\
\end{array}\)

 

[mommy99]

thank you : )

 

[amji12]

Less Technical Solution

In addition to the other solution which was right, your niece may find it helpful to read this too:

The Percent of students who got A's is 50% and the Percent of Students who got B's is 12.5

For the working:

Example