PSAT Math Multiple-Choice Question 632: Answer and Explanation

Question: 632

A reporter finds that on average, a particular politician receives 14 seconds of applause out of every minute of a speech. If the politician were to give a speech for exactly two hours, how many minutes of the speech would be devoted to applause?

• A. 14
• B. 28
• C. 37
• D. 1,680

Correct Answer: B

Explanation:

(B) Let's set up a proportion for this problem. The politician receives 14 seconds of applause for every minute of a speech. We want our units to be the same, so let's call that minute 60 seconds. We can model this part of our proportion as .

We want to know how many minutes of applause he'll get for 2 hours of speech. Since we want our answer in minutes, let's call 2 hours 120 minutes. We want applause on top again. Therefore, this side of the proportion can be modeled by , where x represents the number of minutes of applause the politician will receive in 120 minutes.

You can then set both sides of the proportion equal to one another:

Next, cross multiply:

14(120) = 60x
1,680 = 60x

Dividing by 60 gives us x = 28, choice (B).