PSAT Math Grid-Ins Question 77: Answer and Explanation

Question: 77

There are 400 seniors and 420 juniors in a certain high school. Of the seniors, 65% are eligible for an advanced placement world history course. Among the juniors, 75% are not eligible to enroll in that course. How many more seniors than juniors could enroll in the course?

Correct Answer: 155

Explanation:

155

Difficulty: Medium

Category: Percents

Strategic Advice: The total numbers of seniors and juniors are different, so you'll have to apply the given percentages to the number of students in each class to determine the numbers of students eligible for the course in each class, then subtract the results to find the difference. Be careful: the percentage for juniors is stated as those who are NOT eligible.

Getting to the Answer: The number of seniors eligible is . The percentage of juniors who are not eligible is 75%, so the percentage who are eligible is 100% - 75% = 25%. Thus, the number of eligible juniors is . The difference is 260 - 105 = 155. Grid in 155.