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Two Boxes

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Two Boxes

by sk8ternite » Tue Aug 25, 2009 11:07 am
There are two boxes of markers. The first box has only red, orange and yellow markers. The second box has only yellow, green and blue markers. If a marker is chosen at random from each of the boxes, is the probability that both markers will be yellow less than 30%?
(1) Four of the 12 total markers are yellow
(2) The probability of selecting a red or orange marker is 3/5 and the probability of selecting a green or blue marker is 2/7 .
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Source: — Data Sufficiency |
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Re: Two Boxes

by maihuna » Tue Aug 25, 2009 11:15 am
sk8ternite wrote:There are two boxes of markers. The first box has only red, orange and yellow markers. The second box has only yellow, green and blue markers. If a marker is chosen at random from each of the boxes, is the probability that both markers will be yellow less than 30%?
(1) Four of the 12 total markers are yellow
(2) The probability of selecting a red or orange marker is 3/5 and the probability of selecting a green or blue marker is 2/7 .
B: 2/5*5/7 = 2/7 = <30%
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Re: Two Boxes

by sk8ternite » Tue Aug 25, 2009 11:53 am
maihuna wrote:
sk8ternite wrote:There are two boxes of markers. The first box has only red, orange and yellow markers. The second box has only yellow, green and blue markers. If a marker is chosen at random from each of the boxes, is the probability that both markers will be yellow less than 30%?
(1) Four of the 12 total markers are yellow
(2) The probability of selecting a red or orange marker is 3/5 and the probability of selecting a green or blue marker is 2/7 .
B: 2/5*5/7 = 2/7 = <30%
https://www.beatthegmat.com/a/2009/08/25 ... n-pitfalls

How come A cant be right, Ive tried different combinations and always get less than 30%. We know that there are 4 yellow markers and 12 total markers, so creating different scenarios, I always get under 30%, unless im doing something wrong?
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by pradeepsarathy » Tue Aug 25, 2009 12:38 pm
IMO D

Stmt 1 -

Probability of selecting yellow markers can be found - 4C2 / 12C2
Sufficient

Stmt 2 -

Probability of selecting a yellow marker from the first box is 1 - 3/5 = 2/5
Probability of selecting a yellow marker from the second box is 1 - 2/7 = 5/7

Hence probabiltiy of selecting yellow markers from both the box is 2/5 * 5/7 = 2/7
Sufficient
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