Median number of pages for all books on 2 shelves?

This topic has expert replies
Junior | Next Rank: 30 Posts
Posts: 24
Joined: Tue May 29, 2012 3:30 pm
#47

A certain bookcase has 2 shelves of books. On the upper shelf, the book with the greatest number of pages has 400 pages. On the lower shelf, the book with the least number of pages has 475 pages. What is the median number of pages for all of the books on the 2 shelves?

1) There are 25 books on the upper shelf.

2) There are 24 books on the lower shelf.

User avatar
MBA Admissions Consultant
Posts: 2279
Joined: Fri Nov 11, 2011 7:51 am
Location: New York
Thanked: 660 times
Followed by:266 members
GMAT Score:770

by Jim@StratusPrep » Tue May 29, 2012 4:21 pm
1 and 2 are each insufficient individually because you do not know the total number of books in either case.

Together, you know that the 25th longest (or shortest) book is the median. On the upper shelf you know that the longest book of the 25 has to have 400 pages, placing it at the median.
GMAT Answers provides a world class adaptive learning platform.
-- Push button course navigation to simplify planning
-- Daily assignments to fit your exam timeline
-- Organized review that is tailored based on your abiility
-- 1,000s of unique GMAT questions
-- 100s of handwritten 'digital flip books' for OG questions
-- 100% Free Trial and less than $20 per month after.
-- Free GMAT Quantitative Review

Image