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Section - 21 Question - 16

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by camitava » Wed Sep 19, 2007 2:47 am
Guys answer my question. I am stuck to it. Tell me the approach also -
Of the science books in a certain supply room, 50 are on botany, 65 are on zoology, 90 are on physics. 50 are on geology, and 110 are on chemistry. If science books are removed randomly from the supply room, how many must be removed to ensure that 80 of the books removed are on the same science?
(A) 81
(B) 159
(C) 166
(D) 285
(E) 324
Refer below -
[spoiler]E is the answer. -> Look Eric I have used it!!!! (Ha ha ha)...[/spoiler]
Correct me If I am wrong


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Amitava
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by kajcha » Wed Sep 19, 2007 2:53 am
E is the answser

Q is asking 80 of the same science.. and only physics and chem are more than 80.. so worst case scenario

One needs to remove all of zoology, botany and geology books and 79 each of phys and chem

so total is 50+50+65+79+79 = 324.

Next one removed will be 80th one of either phys or chem
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by camitava » Wed Sep 19, 2007 2:58 am
Kajcha, Thanks! But can u pls explain the approach little elaborately? Or I am getting the wrong sense of the question? From the qs, I am getting -
We have to remove books from the self and qs is asking the number of books to be removed from the self so that 80 books of the removed one are of same science. Am i right? Or it is asking something else? Pls help me out!
Correct me If I am wrong


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by kajcha » Wed Sep 19, 2007 3:07 am
I think you understood right..

Let me put this way
Biology = Botany = 50 books
Zoology = 65
Chem = 110
Phys = 90

Q is concerned about removing 80 books of same science. This can happen only with Chem and Phys, right?

Now, think of worst case scenario

One has removed all the books for Bio, Zoo and Bot.
79 each of Chem and Phy

So next book that willl be removed will be either phy or chem.. and that would be the 80th book, for sure, of that science, right?

means by the time you take out the 325th book, you will be dead sure that 80 books of same science are removed...

Hope this clears your doubt...
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by camitava » Wed Sep 19, 2007 3:50 am
Wohhhhhhhh! Great... Got it. Thanks a lot man. Thanks once again for explaining so clearly. Really ur math conception is appreciable! :wink: :lol:
Correct me If I am wrong


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