# SAT Math Multiple Choice Question 219: Answer and Explanation

### Test Information

Question: 219

9. Monster Truck Inc. leases a new truck for a down payment of \$3,200 plus monthly payments of \$380 per month for 36 months. Which of the following functions f represents the total amount paid, in dollars, after m months, where 0 ≤ m ≤ 36 ?

• A. f(m) = 380 + 3,200m
• B. f(m) = 3,200 + 36m
• C. f(m) = 3,200 + 380m
• D. f(m) = 10,480 - 380m

Explanation:

C Whenever there are variables in the question and in the answers, think Plugging In. If m = 10, then Monster Truck Inc., receives a down payment of \$3,200 plus 10 months' worth of monthly payments. This can be calculated as 3,200 + 10(380) = 3,200 + 3,800 = \$7,000. Plug in 10 for m in the answers to see which function equals 7,000. Choice (A) becomes f(m) = 380 + 3,200(10) = 380 + 32,000 = 32,380. Eliminate (A). Choice (B) becomes f(m) = 3,200 + 36(10) = 3,200 + 360 = 3,560. Eliminate (B). Choice (C) becomes f(m) = 3,200 + 380(10) = 3,200 + 3,800 = 7,000. Keep (C), but check (D) just in case it also works. Choice (D) becomes f(m) = 10,480 - 380(10) = 10,480 - 3,800 = 6,680. Eliminate (D). The correct answer is (C).