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In a jar there are 15 white balls, 25 red balls, 10 blue 17 Jan 2006, 18:07
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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



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In a jar there are 15 white balls, 25 red balls, 10 blue 17 Jan 2006, 18:39
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Himalaya, can you enlighten us ?! I gave up after 2 minutes...
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HIMALAYA
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In a jar there are 15 white balls, 25 red balls, 10 blue 17 Jan 2006, 18:43
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lhotseface
Himalaya, can you enlighten us ?! I gave up after 2 minutes...
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let me correect it as 29 not 32.

till taking out 28 balls, you might not get 8 balls of same color cuz you have the possibility of getting 7 balls of each color. when u get the next ball, it must be one of the four colors, making one of the color balls 8.
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In a jar there are 15 white balls, 25 red balls, 10 blue 17 Jan 2006, 18:55
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I am lost. Can you please show your working when you get a chance..thanks.

HIMALAYA
lhotseface
Himalaya, can you enlighten us ?! I gave up after 2 minutes...
let me correect it as 29 not 32.

till taking out 28 balls, you might not get 8 balls of same color cuz you have the possibility of getting 7 balls of each color. when u get the next ball, it must be one of the four colors, making one of the color balls 8.
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In a jar there are 15 white balls, 25 red balls, 10 blue 17 Jan 2006, 18:57
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We have to go by the worst case scenario here. Take out balls one of each color every time. So after you take out 28 ball we have 7 balls of each color. The 29th ball will make sure that one color will finally have all 8 balls. It may happen before that but that many balls are needed to make sure we draw 8 balls of one particular color.
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In a jar there are 15 white balls, 25 red balls, 10 blue 17 Jan 2006, 19:03
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Pull out 7 of 25 red, 7 of 15 white, 7 of 10 blue, and 7 of 20 green. That equals 28 balls without pulling out 8 of any particular color. Pull out one more ball and you will have 8 of one of the colors. All together that makes 29 balls.
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In a jar there are 15 white balls, 25 red balls, 10 blue 17 Jan 2006, 19:05
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I got it. Didn't think hard enough.

Thanks to Bhai as well.

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lhotseface
Himalaya, can you enlighten us ?! I gave up after 2 minutes...
let me correect it as 29 not 32.

till taking out 28 balls, you might not get 8 balls of same color cuz you have the possibility of getting 7 balls of each color. when u get the next ball, it must be one of the four colors, making one of the color balls 8.
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In a jar there are 15 white balls, 25 red balls, 10 blue 17 Jan 2006, 19:13
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lhotseface
I got it. Didn't think hard enough.

Thanks to Bhai as well.

HIMALAYA
lhotseface
Himalaya, can you enlighten us ?! I gave up after 2 minutes...
let me correect it as 29 not 32.

till taking out 28 balls, you might not get 8 balls of same color cuz you have the possibility of getting 7 balls of each color. when u get the next ball, it must be one of the four colors, making one of the color balls 8.
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gr8. its a real gmat type question. so it is better for anybody to note this question.
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Bhai
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In a jar there are 15 white balls, 25 red balls, 10 blue 17 Jan 2006, 19:14
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You are welcome :!:
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In a jar there are 15 white balls, 25 red balls, 10 blue 17 Jan 2006, 22:58
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yups 29 it is
7*4+1
7 in best case scenario and 1 in worst case
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In a jar there are 15 white balls, 25 red balls, 10 blue 18 Jan 2006, 02:36
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Lets take each ball one by one of different color in any order.

Say 1W then 1R then 1B and 1G. (May be any order)

Do it seven times. Now we have 28 balls.

Now you take any color ball. After this we will have atleast one set of 8 ball of the same color.

So its 7* 4 + 1= 29



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Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
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