Question

In a class consisting of $10$ boys and $15$ girls, the average score on a maths test is $90$. If the average score of the girls is $x$, find the average score for the boys in terms of $x$.

• A. $200-\frac{2}{3}x$
• B. $225-\frac{3}{2}x$
• C. $250-2x$
• D. $250-3x$
• E. $275-2x$

Answer 1

Answer: (B)

$225-\frac{3}{2}x$

Totally there are $25$ students and the average of $25$ students in maths is $90$ , so total score obtained is $90\times 25$.

Average score of girls is $x$ , total score obtained by girls will be $15\times x$

Therefore, total score obtained by boys is $90\times 25-15\times x$

Average score is $\frac{(90\times 25-15\times x)}{10}=225-\frac{3x}{2}$