|Total GMAT Math
Jeff's complete Quant guide, on sale now!
|Total GMAT Verbal
Everything you need to ace GMAT Verbal!
1,800 Practice Math Questions
Buy Jeff's books at Amazon.com
GMAT Official Guide, with IR
OG Math | OG Verbal
OG12 & Quant Rev solutions!
GMAT Question of the Day
Beginner's Guide to the GMAT
GMAT Hacks Affiliate Program
- General Study Tips
- Goals and Planning
- CAT Strategy
- The Mental Game
- GMAT Math Strategy
- GMAT Math Topics
- Mental Math
- Data Sufficiency
- Critical Reasoning
- Reading Comprehension
- Sentence Correction
- Analytical Writing Assessment
- Integrated Reasoning
- IR Explained
- Business School Admissions
- GMAT Prep Resources
- Practice Questions
- Total GMAT Math
- Total GMAT Verbal
- GMAT 111
IR Explained: Q25: Exercising For Hours
August 6, 2012
|You should follow me on Twitter. While you're at it, take a moment to subscribe to GMAT Hacks via RSS or Email.|
While this bar graph comes with an explanation, it is still somewhat difficult to understand. The leftmost bar, with a height of 5, does not refer to 0 hours or 1 hours, it refers to "at least zero, and less than one." So 5 adults reported exercising at least zero hours, but less than one hour.
By the same reasoning, the next bar to the right, with a height of 3, means that 3 adults reported exercising for at least one hour, but less than two hours. This vagueness makes precise calculations impossible, a characteristic that one of the two questions will capitalize on.
25A asks for the "least possible value" of the average amount of exercise for the 25 respondents. As we've seen, each respondent is claiming an amount of exercise within a certain range--not a specific amount.
For the "least possible" mean, take each respondent's least possible number of hours. The 5 zero-to-ones are 0, the 3 one-to-twos are 1, the 2 two-to-threes are 2, and so on.
The sum of all the respondents' hours is as follows: 5(0) + 3(1) + 2(2) + 4(3) + 4(4) + 5(5) + 1(8) + 1(10) = 0 + 3 + 4 + 12 + 16 + 25 + 8 + 10 = 78. Since there are 25 respondents, the average is 78/25, or 3 3/25. Don't worry about the precise decimal conversion--given the options available, it must be 3.12.
25B is not nearly so involved. Half an hour per day is 3.5 hours per week. Thus, anyone who exercised less than three hours definitely averaged less than one-half hour per day. That encompasses the leftmost three bars: 5 0-to-1s, 3 1-to-2s, and 2 2-to-3s, for a total of 10.
The 4 3-to-4-hour respondents might average less than one-half hour day, or they might average more. Thus, the total could be as little as 10, or as many as 14: between 10 and 14, inclusive.
Stay tuned (or subscribe) for more Integrated Reasoning explanations
About the author: Jeff Sackmann has written many GMAT preparation books, including the popular Total GMAT Math, Total GMAT Verbal, and GMAT 111. He has also created explanations for problems in The Official Guide, as well as 1,800 practice GMAT math questions.
|Total GMAT Verbal
The comprehensive guide to the GMAT Verbal section. Recognize, dissect, and master every question type
you'll face on the test. Everything you need, all in one place, including 100+ realistic practice questions.