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## Official Guide Explanation:

Data Sufficiency #4

**Background**

This is just one of hundreds of free explanations I've created to the quantitative questions in The Official Guide for GMAT Review (12th ed.). Click the links on the question number, difficulty level, and categories to find explanations for other problems.

These are the same explanations that are featured in my "Guides to the Official Guide" PDF booklets. However, because of the limitations of HTML and cross-browser compatibility, some mathematical concepts, such as fractions and roots, do not display as clearly online.

Click here for an example of the PDF booklets. Click here to purchase a PDF copy.

**Solution and Metadata**

**Question****: 4**

Page: 273

Difficulty: **5** (Moderate)

Category 1: Word Problems > Sets >

Category 2: Arithmetic > Sets > 2 sets

**Explanation:** Since the question is somewhat elliptical, first try to understand what it's asking. Presumably, there are some students in a chemistry course, some students in a biology course, and some students who are not in either one. The question wants to know whether there are more students in both courses than the number in neither course.

Statement (1) is not sufficient. The number of students in chemistry doesn't tell us the number in both or the number in neither.

Statement (2) is not sufficient by the same reasoning as (1).

Taken together, the statements are still not sufficient. There could be anywhere between 0 and 60 students enrolled in both courses. And without knowing the total number of students at the college, we don't know how many are enrolled in neither course. Choice (E) is correct.

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