There are 200 questions on a 3-hour examination. Among these questions 50 are mathematics problems. It is suggested that twice as much time be spent on each math problem as for each other question. How many minutes should be spent on mathematics problems?

First, since we're talking about minutes, convert 3 hr into minutes: 3X60 = 180 minutes Let x = minutes spent on a non-math problem then, 2x = minutes spent on a math problem Here, x(200-50) + 2x(50) = 180 x(150) + 2x(50) = 180 150x + 100x = 180 250x = 180 x = 0.72 minutes Time to spend on math problems: 2x(50)=100x = 100(0.72) = 72 minutes