There are 20 purple balls and 30 yellow balls in box A. : Quant Question Archive [LOCKED]
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# There are 20 purple balls and 30 yellow balls in box A.

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There are 20 purple balls and 30 yellow balls in box A. [#permalink]

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13 Apr 2005, 13:40
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

There are 20 purple balls and 30 yellow balls in box A. There are 15 purple balls and 35 yellow balls in box B. What is the probability that one ball selected randomly from the 2 box is purple?
VP
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13 Apr 2005, 13:49
20/50+15/50=35/50=7/10
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13 Apr 2005, 14:24
close but no there yet
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13 Apr 2005, 14:44
i also got 7/10.

Let me try again
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13 Apr 2005, 14:55
DLMD wrote:
There are 20 purple balls and 30 yellow balls in box A. There are 15 purple balls and 35 yellow balls in box B. What is the probability that one ball selected randomly from the 2 box is purple?

1/2(20/50 + 15/50) = 7/20
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13 Apr 2005, 15:09
gmat2me2 wrote:
DLMD wrote:
There are 20 purple balls and 30 yellow balls in box A. There are 15 purple balls and 35 yellow balls in box B. What is the probability that one ball selected randomly from the 2 box is purple?

1/2(20/50 + 15/50) = 7/20

pls explain the 1/2.
Thanks
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13 Apr 2005, 15:23
Folaa3 wrote:
gmat2me2 wrote:
DLMD wrote:
There are 20 purple balls and 30 yellow balls in box A. There are 15 purple balls and 35 yellow balls in box B. What is the probability that one ball selected randomly from the 2 box is purple?

1/2(20/50 + 15/50) = 7/20

pls explain the 1/2.
Thanks

2 boxes from which we need to select one purple ball

So select the box first = 1/2
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13 Apr 2005, 20:27
As I understand it, we are selecting just one purple ball from both the boxes together.

So it would be

(20+15)/(50+50) = 35/100 = 7/20
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13 Apr 2005, 20:56
aks720 wrote:
As I understand it, we are selecting just one purple ball from both the boxes together. So it would be (20+15)/(50+50) = 35/100 = 7/20

nice one. or alternatively, 0.5(20/50)+0.5(15/50)=1/5+3/20=7/20.
13 Apr 2005, 20:56
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