If the average of a number, its 75\% and its 25\% is 240, then the number is
(a)280
(b)320
(c)360
(d)400
Answer
Answer (as printed): C
Explanation
Let the number be $x$. Then, $\frac{x+75\% \text{ of } x+25\% \text{ of } x}{3}=240$ $$\Rightarrow x+\frac{75}{100} x+\frac{25}{100} x=240 \times 3=720$$ $$\Rightarrow x+\frac{3}{4} x+\frac{1}{4} x=720 \Rightarrow 2 x=720 \Rightarrow x=360.$$
Explanation as extracted from the printed page; notation may be imperfect.