PSAT Math Multiple-Choice Question 309: Answer and Explanation

Question: 309

Ibrahim has a contract for a cell phone plan that includes the following rates: the plan has a fixed cost of $50 per month, a data plan that provides 2 gigabytes (GB) of data for free and $8 for each GB of data after that, and a text message plan that costs $0.10 per text message sent. Which of the following equations represents the amount of money, in dollars, that Ibrahim will spend as long as he uses at least 2 GB of data? (Assume d = dollars, g = number of GB of data used, and t = number of text messages sent.)

• A. d = 50 + 8g + 0.1t
• B. d = 50 + (8g - 2) + 0.1t
• C. d = 50 + 8(g - 2) + 0.1t
• D. d = 5,000 + 800g + 10t

Correct Answer: C

Explanation:

C

Difficulty: Medium

Getting to the Answer: You know there will be a flat fee of $50, and for text messages you'll be looking for 0.1t. This eliminates (D). If you're stuck on the data plan cost, plug in some numbers. For g = 2, you wouldn't expect there to be an additional fee for data usage. For g = 3, you'd expect to see an $8 charge, and for g = 4, you'd expect to see a $16 charge. The only choice that reflects this is (C).