During the past month, a disease control center tested X individuals for two viruses. If 1/3 of those tested had virus C and, of those with virus C, 1/5 also had virus D, how many individuals did not have both virus C and D?
E. 4 / 5
The number of individuals that had virus C is 1/3 of X, or X/3.
The number of individuals that also had virus D is 1/5 of the number that had virus C.
Thus (1/5)C= (1/5)(X/3) = X/15.
If X/15 of the X individuals have virus C and D, then X - (X/15) did not have both virus C and D.
Neither C or D: X - (X/15) = 14X/15.
The correct answer is D.
Essential GMAT Reading Comprehension Guide
After reading F1GMAT’s Essential GMAT Reading Comprehension Guide, you will:
1. Complete GMAT RC Questions in less than 1 minute and 50 seconds
2. Read Faster
3. Take Notes Effectively
4. Collect and Interpret Facts
5. Speed up Summary Creation
6. Remember Information
7. Question the Author
8. Learn to Answer GMAT Reading Comprehension Title question
9. Learn to Answer GMAT Reading Comprehension Main Idea Question
Mastering GMAT Critical Reasoning
After you read F1GMAT’s Mastering GMAT Critical Reasoning Guide, you will learn:
How to overcome flawed thinking in GMAT Critical Reasoning?