There are 200 questions on a 3 hour examination. Among these questions are 50 Mathematics problems. It is suggested that twice as much time be spent on each Maths problem as for each other question. How many minutes should be spent on Mathematics problems?
(a)36
(b)60
(c)72
(d)100
Answer
Answer (as printed): C
Explanation
Let the time spent on each Maths problem be $(2 x)$ minutes and that spent on each other question be $x$ minutes. Then, $50 \times 2 x+150 x=3 \times 60 \Leftrightarrow 250 x=180$ $$\Leftrightarrow x=\frac{180}{250}=\frac{18}{25} .$$ ∴ Total time spent on Mathematics problems $$=\left(50 \times 2 \times \frac{18}{25}\right) \min =72 \mathrm{min} .$$