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28 Oct 2011, 23:07
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A
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Difficulty:
55%
(hard)
Question Stats:
59% (01:43) correct
41%
(01:54)
wrong
based on 347
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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
A. 20
B. 23
C. 25
D. 28
E. None of these
07 Dec 2017, 09:49
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lichting
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.
General Discussion
29 Oct 2011, 06:14
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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.
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.
