Author 
Message 
TAGS:

Hide Tags

Intern
Joined: 27 Sep 2011
Posts: 14

There are 9 novel books, 4 drama books, 12 poetry books and 7 grammar [#permalink]
Show Tags
28 Oct 2011, 23:07
Question Stats:
62% (01:07) correct 38% (01:29) wrong based on 176 sessions
HideShow timer Statistics
There are 9 novel books, 4 drama books, 12 poetry books and 7 grammar books in my bookshelf. The books are randomly arranged in the shelf and not at all in the order of their type. What is the least number of books that must be drawn from the shelf in order to get 6 books of a particular type? a) 20 b) 23 c) 25 d) 28 e) None of these
Official Answer and Stats are available only to registered users. Register/ Login.
_________________
All I want to be A Selfmade Man



Intern
Joined: 03 Oct 2011
Posts: 24

Re: There are 9 novel books, 4 drama books, 12 poetry books and 7 grammar [#permalink]
Show Tags
29 Oct 2011, 06:14
Is the ans a ?
Suppose we need to draw 20 books. Considering the worst case, If we remove all drama books that is 4 of them are gone out of 20 left with 16. Now suppose 5 of each novel, poetry and drama are drawn out from the shelf, that is 15 more books gone, so total 19 are taken out from the shelf and left with 1. Now the next 1 book which is pulled can be any of the three categories but it would definitely complete a set of 6 for one of the them.
Best case would be the first 6 we draw are of the same category. But if we pull 20 out atleast 1 of them would complete a set of 6.



Manager
Joined: 29 Oct 2011
Posts: 166
Concentration: General Management, Technology
GPA: 3.76

Re: There are 9 novel books, 4 drama books, 12 poetry books and 7 grammar [#permalink]
Show Tags
01 Nov 2011, 14:53
Agreed.
This is a problem where you need to consider worst case:
1. Take out 4 Dramas. 2. Take 5 of each of the other 3, total of 15. 3. Next book you take will complete a set of 6.
Total is 4+15+1 = 20.
A



Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 2779
Location: United States (CA)

Re: There are 9 novel books, 4 drama books, 12 poetry books and 7 grammar [#permalink]
Show Tags
24 Oct 2017, 06:43
aselfmademan wrote: There are 9 novel books, 4 drama books, 12 poetry books and 7 grammar books in my bookshelf. The books are randomly arranged in the shelf and not at all in the order of their type. What is the least number of books that must be drawn from the shelf in order to get 6 books of a particular type?
a) 20 b) 23 c) 25 d) 28 e) None of these Let’s assume the worst case scenario. Let’s say we have drawn 5 novels, all 4 drama books, 5 poetry books, and 5 grammar books; we would have a total of 19 books drawn but still not have 6 books of one type. However, if we draw just one more book (which must be a novel, poetry, or a grammar book), we would have 6 books of one particular type. Thus, the least number of books that must be drawn is 20. Answer: A
_________________
Scott WoodburyStewart
Founder and CEO
GMAT Quant SelfStudy Course
500+ lessons 3000+ practice problems 800+ HD solutions



Manager
Joined: 17 Sep 2017
Posts: 61

Re: There are 9 novel books, 4 drama books, 12 poetry books and 7 grammar [#permalink]
Show Tags
07 Dec 2017, 09:35
I still do not understand. Can anyone please give more explaination on this question?



Math Expert
Joined: 02 Sep 2009
Posts: 46319

Re: There are 9 novel books, 4 drama books, 12 poetry books and 7 grammar [#permalink]
Show Tags
07 Dec 2017, 09:49
lichting wrote: I still do not understand. Can anyone please give more explaination on this question? There are 9 novel books, 4 drama books, 12 poetry books and 7 grammar books in my bookshelf. The books are randomly arranged in the shelf and not at all in the order of their type. What is the least number of books that must be drawn from the shelf in order to get 6 books of a particular type?a) 20 b) 23 c) 25 d) 28 e) None of these The question asks to find the least number of books we should pick to guarantee that we have 6 books of one particular type. In such questions we should consider the worst case scenario which could happen. This would be if we pick all 4 drama books, 5 novel books, 5 poetry books, and 5 grammar books, so total of 19 books. In this case we still wouldn't have 6 books of one type. But the next, 20th, book we pick, be it novel, poetry or grammar book, would make 6 books for one of these types. Answer: A. Check other Worst Case Scenario Questions from our Special Questions Directory to understand the concept better.
_________________
New to the Math Forum? Please read this: Ultimate GMAT Quantitative Megathread  All You Need for Quant  PLEASE READ AND FOLLOW: 12 Rules for Posting!!! Resources: GMAT Math Book  Triangles  Polygons  Coordinate Geometry  Factorials  Circles  Number Theory  Remainders; 8. Overlapping Sets  PDF of Math Book; 10. Remainders  GMAT Prep Software Analysis  SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS)  Tricky questions from previous years.
Collection of Questions: PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.
What are GMAT Club Tests? Extrahard Quant Tests with Brilliant Analytics




Re: There are 9 novel books, 4 drama books, 12 poetry books and 7 grammar
[#permalink]
07 Dec 2017, 09:49






