PSAT Math Multiple-Choice Question 143: Answer and Explanation

Question: 143

A student planned to finish her summer reading assignment over the course of a 20-day portion of her summer vacation. Each day, she recorded the percent of her assignment she had left to read. The graph below shows the data for each day of the 20-day portion of her summer vacation.

During which of the following periods is the decrease in the percent of her remaining summer reading the least?

• A. Days 1 though 5
• B. Days 3 through 8
• C. Days 7 through 12
• D. Days 13 through 17

Correct Answer: A

Explanation:

A

The question asks for the period that shows the least decrease. Ballpark to find the answer. Choice (A) has a decrease of about one interval between horizontal gridlines. Choice (B) has a decrease of about more than two full intervals. Choice (C) has a decrease of about 4 intervals. Choice (D) has a decrease of about 2 intervals. Therefore, the correct answer is (A).