Events & Promotions
|
|
GMAT Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized
for You
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Apr 2308:00 PM PDT
-09:00 PM PDT
Video explanations + diagnosis of 10 weakest areas + 150+ short videos + study plan!
Apr 2301:30 AM EDT
-02:30 AM EDT
Struggling with GMAT Verbal as a non-native speaker? Harsh improved his score from 595 to 695 in just 45 days—and scored a 99 %ile in Verbal (V88)! Learn how smart strategy, clarity, and guided prep helped him gain 100 points.
Apr 2512:30 AM EDT
-01:30 AM EDT
At one point, she believed GMAT wasn’t for her. After scoring 595, self-doubt crept in and she questioned her potential. But instead of quitting, she made the right strategic changes. The result? A remarkable comeback to 695. Check out how Saakshi did it.
Apr 2610:00 AM EDT
-11:00 AM EDT
The Target Test Prep course represents a quantum leap forward in GMAT preparation, a radical reinterpretation of the way that students should study. Try before you buy with a 5-day, full-access trial of the course for FREE!
Apr 2711:00 AM EDT
-12:00 PM EDT
Prefer video-based learning? The Target Test Prep OnDemand course is a one-of-a-kind video masterclass featuring 400 hours of lecture-style teaching by Scott Woodbury-Stewart, founder of Target Test Prep and one of the most accomplished GMAT instructors
Apr 2808:00 AM PDT
-11:00 AM PDT
Whether you are just beginning your MBA journey or fine-tuning your path to a 700+ score, GMAT Day is designed to give you a competitive edge.
10 Nov 2022, 07:54
Kudos
Bookmarks
D
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
95%
(hard)
Question Stats:
36% (01:40) correct
64%
(01:46)
wrong
based on 106
sessions
History
Date
Time
Result
Not Attempted Yet
40 DVDs (17 are about psychology, 14 are about biology, and 9 are about history) need to be arranged in a bookshelf such that the 9 history-related DVDs are, on the whole, arranged in chronological order. In how many ways can these DVDs be arranged?
A. \(17!*14!*3!\)
B. \(17!*14!*9!\)
C. \(17!*14!*9!*39\)
D. \(\frac{40!}{9!}\)
E. \(32!\)
A. \(17!*14!*3!\)
B. \(17!*14!*9!\)
C. \(17!*14!*9!*39\)
D. \(\frac{40!}{9!}\)
E. \(32!\)
10 Nov 2022, 09:25
Kudos
Bookmarks
So we have three sets of DVDs - psychology, biology and history. These DVDs can be arranged in any order, except 9 history-related DVDs are, on the whole, needs to be arranged in chronological order.
In total we have 40 DVD , these DVDs can be arranged in 40! ways.
Now note, that in this arrangement we have considered all possible arrangements of the history related DVDs as well. However, only one arrangement is possible for the history related DVDs. Hence we need to un-arrange them. Hence the 9! ways in which the DVDs could have been arranged needs to be factored out.
Total number of ways = \(\frac{40! }{ 9!}\)
IMO D
In total we have 40 DVD , these DVDs can be arranged in 40! ways.
Now note, that in this arrangement we have considered all possible arrangements of the history related DVDs as well. However, only one arrangement is possible for the history related DVDs. Hence we need to un-arrange them. Hence the 9! ways in which the DVDs could have been arranged needs to be factored out.
Total number of ways = \(\frac{40! }{ 9!}\)
IMO D
19 Nov 2022, 06:46
Kudos
Bookmarks
But the 9 history-related DVDs are, on the whole, arranged in chronological order. So they can be considered as a single DVD. And thereby the total ways could be 32!. Why are the arrangement of 9 DVDs getting divided? Shouldn't division be done when the objects are identical?
