Question

The average (arithmetic mean) of all the grades on a certain algebra test was $90$. If the average of the $8$ males grades was $87$, and the average of the females grades was $92$, calculate the number of female students.

• A. 8
• B. 9
• C. 10
• D. 11
• E. 12

Answer 1

The correct option is E 12

Let the female students be $x$ and male students is $8$, so the total number of students is $x+8$
$\Rightarrow 90(x+8)=87\times 8+92x$
$\Rightarrow 2x=24$

$\Rightarrow x=12$