PSAT Math Multiple-Choice Question 541: Answer and Explanation

Question: 541

Maria can use which of the following inequalities to model the number of days, d, she can use her phone before she hits or goes over her limit of 7 Gigabytes?

• A. 2d + 0.5 ≤ 7
• B. 2 + 0.5d ≤ 7
• C. 2 ≤ 0.5d + 7
• D. 2 ≤ 0.5 + 7d

Correct Answer: B

Explanation:

B

The question asks for an inequality that models a specific situation. Translate the English to math in bite-sized pieces. The days are represented as d. The inequality must show the number of days before she hits or goes over her limit or 7 Gigabytes. This means that the expression containing d must be less than or equal to 7, which is represented as "≤ 7." Eliminate (C) and (D), as the expression for days is not less than or equal to 7. The question asks about data use of 2 hours each day and 0.25 Gigabytes for each of those hours, so Maria uses 0.25(2) = 0.5 Gigabytes of data each day, represented as 0.5d. Eliminate (A), as it does not show 0.5 Gigabytes used each day. The correct answer is (B).