Source: Official Guide for the GMAT 12th Ed. Section 5.3 Problem Solving; #221

1

Of the 200 students at College T majoring

Of the 200 students at College T majoring in one or more of the sciences, 130 are majoring in chemistry and 150 are majoring in biology. If at least 30 of the students are not majoring in either chemistry or biology, then the number of students majoring in both chemistry and biology could be any number from 20 to 50, 40 to 70, 50 to 130, 110 to 130, 110 to 150

2 Explanations

1

Rob

I'm confused. The wording "Of the 200 students at College T majoring in one or more of the sciences" implies the that the total is not 200. We don't know that the kids who studied neither Biology nor Chemistry studied any science, right?

May 15, 2016 • Comment

Cydney Seigerman, Magoosh Tutor

Hi Rob :)

Happy to help! I can see how the wording can be confusing. However, the phrase "Of the 200 students at College T majoring in one or more of the sciences" indicates that the question will be dealing with that group of 200 students. Our set is the 200 students who are studying at least one science. For example, when the prompt says "If at least 30 of the students", "the students" refers to the group of 200 studying at least 1 science. And with that, we can be sure that these students do study at least 1 science. :)

I hope that clears up your doubt!

May 18, 2016 • Reply

2

Gravatar Mike McGarry, Magoosh Tutor

Nov 8, 2012 • Comment

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Section 5.3 Problem Solving

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