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Bloody jail and balls taken out

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Bloody jail and balls taken out

by acorra » Sat Sep 27, 2008 3:31 am
In a jar there are 15 white balls, 25 red balls, 10 blue balls and 20 green balls. How many balls must be taken out in order to make sure we took out 8 of the same color?

a) 8
b) 23
c) 29
d) 32
e) 53

Please explain with all possible methods (if there is more than one).

Thanks
Andrew
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by stop@800 » Sat Sep 27, 2008 3:48 am
You need 8 balls of one color

For maximum balls it has to be (n-1) of all but one colors and n of last colors.

Like:
We need 8 same colored balls
it may happen that i selected 7 balls and all are of same color
i slected next and its of diffrent color
and next 7 makes another color
so at end I may end up with

7 White
7 Red
7 Blue and
7 Green

and any 1 more ball will make 8 balls of 1 color
so in worst case we need 28 + 1 = 29 balls.





n = 8
and colors = 4

(8-1) * (4-1) + 8
=29

Hope this helps!!
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by acorra » Sat Sep 27, 2008 7:49 am
Man, are you seeking the worse scenario, because the the question asks you to [b]make sure[/b]? Otherwise you'll go on with the usual calculation?

is it that the reason?

thanks
Andrew[/b]
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