PSAT Math Grid-Ins Question 11: Answer and Explanation

Question: 11

15% of the members of the incoming freshmen class at a certain university are left-handed, and the remaining members are right-handed. 65% of the same incoming freshmen class are female, and the rest are male. If of the left-handed students are male, then what percent of the female class is right-handed, to the nearest tenth of a percent? (Disregard the percent sign when gridding your answers. For example, if the answer is 43.2%, grid in 43.2.)

Correct Answer: 92.3

Explanation:

92.3

The question asks for a percent. The question does not say how many students are in the freshman class, so that is a hidden variable. When a question asks for a percent of an unknown quantity, plug in. Because the question is about percentages, make the total number of students 100. That means that there are 15 left-handed students and 85 right-handed students in the class. There are also 65 female students and 35 male students. If of the left-handed students are male, then there are male left-handed students. This leaves 15 - 10 = 5 female left-handed students. If 5 of the 65 female students are left-handed, then the other 60 female students are right-handed. To find the percentage of female students who are right-handed, divide: 60 ÷ 65 = 0.923. Remember to multiply a decimal by 100 to get the equivalent percentage, which is 92.3%. The correct answer is 92.3.