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A box contains 4 red chips and 2 blue chips. If two chips are selected at random without replacement, what is the probab

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A box contains 4 red chips and 2 blue chips. If two chips are selected at random without replacement, what is the probab

by BTGModeratorVI » Wed Oct 07, 2020 7:18 am

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A box contains 4 red chips and 2 blue chips. If two chips are selected at random without replacement, what is the probability that the chips are different colors?

A. 1/2
B. 8/15
C. 7/12
D. 2/3
E. 7/10

Answer: B
Source: Magoosh
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Re: A box contains 4 red chips and 2 blue chips. If two chips are selected at random without replacement, what is the pr

by Brent@GMATPrepNow » Fri Oct 09, 2020 10:13 am
BTGModeratorVI wrote: ↑
Wed Oct 07, 2020 7:18 am
 A box contains 4 red chips and 2 blue chips. If two chips are selected at random without replacement, what is the probability that the chips are different colors?

A. 1/2
B. 8/15
C. 7/12
D. 2/3
E. 7/10

Answer: B
Source: Magoosh
P(different colors) = P(1st chip is red and 2nd chip is blue OR 1st chip is blue and 2nd chip is red)
= P(1st chip is red and 2nd chip is blue) + P(1st chip is blue and 2nd chip is red)
= P(1st chip is red) x P(2nd chip is blue) + P(1st chip is blue) x P(2nd chip is red)
= 4/6 x 2/5 + 2/6 x 4/5
= 8/30 + 8/30
= 16/30
= 8/15

Answer: B

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Brent
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Re: A box contains 4 red chips and 2 blue chips. If two chips are selected at random without replacement, what is the pr

by Scott@TargetTestPrep » Fri Oct 16, 2020 5:49 am
BTGModeratorVI wrote: ↑
Wed Oct 07, 2020 7:18 am
 A box contains 4 red chips and 2 blue chips. If two chips are selected at random without replacement, what is the probability that the chips are different colors?

A. 1/2
B. 8/15
C. 7/12
D. 2/3
E. 7/10

Answer: B
Solution:

To satisfy the requirement, we must obtain either R-B or B-R. Thus, we need to determine:

P(red) x P(blue) + P(blue) x R(red)

4/6 x 2/5 + 2/6 x 4/5 = 2/3 x 2/5 + 1/3 x 4/5 = 4/15 + 4/15 = 8/15.

Answer: B

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