SAT Math Multiple Choice Question 841: Answer and Explanation
1. John buys c pounds of cheese to feed m people at a party. If m + n people come to the party, how many more pounds of cheese must John buy in order tofeed everyone at the original rate?
Correct Answer: D
Category: Problem Solving and Data Analysis / Rates, Ratios, Proportions, and Percentages
Strategic Advice: This is a great question in which you can pick convenient numbers to represent the variables given and work through the answer choices using those numbers.
Getting to the Answer: Say John buys 10 pounds of cheese for 5 people (that is, c = 10 and m = 5). Then everyone gets 2 pounds of cheese. Also, say 8 people come, 3 more than expected (that is, n = 3). Then John needs 16 pounds to have enough for everybody to consume 2 pounds of cheese. Because he already bought 10 pounds, he must buy an additional 6 pounds. Therefore, an answer choice that equals 6 when you substitute 10 for c, 5 for m, and 3 for n is the correct choice:
Choice A:. Eliminate.
Choice B:. Eliminate.
Choice C:. Eliminate.
Choice (D):. Choice (D) is correct.