A gardener is going to plant 2 red rosebushes and 2 white rosebushes. If the gardener is to select each of the bushes at

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A gardener is going to plant 2 red rosebushes and 2 white rosebushes. If the gardener is to select each of the bushes at random, one at a time, and plant them in a row, what is the probability that the 2 rosebushes in the middle of the row will be the red rosebushes?

A. \(\dfrac1{12}\)

B. \(\dfrac16\)

C. \(\dfrac15\)

D. \(\dfrac13\)

E. \(\dfrac12\)

Answer: B

Source: GMAT Paper Tests
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VJesus12 wrote:
Fri Aug 06, 2021 10:20 am
A gardener is going to plant 2 red rosebushes and 2 white rosebushes. If the gardener is to select each of the bushes at random, one at a time, and plant them in a row, what is the probability that the 2 rosebushes in the middle of the row will be the red rosebushes?

A. \(\dfrac1{12}\)

B. \(\dfrac16\)

C. \(\dfrac15\)

D. \(\dfrac13\)

E. \(\dfrac12\)

Answer: B

Source: GMAT Paper Tests
Let's apply some probability rules:

P(2 middle bushes are red) = P(1st bush is white AND 2nd bush is red AND 3rd bush is red AND 4th bush is white)
= P(1st bush is white) x P(2nd bush is red) x P(3rd bush is red) x P(4th bush is white)
= 2/4 x 2/3 x 1/2 x 1/1
= 1/6

Answer: B

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Brent
Brent Hanneson - Creator of GMATPrepNow.com
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