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Scoretop 10 - Question 9

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Scoretop 10 - Question 9

by akay » Thu Sep 27, 2007 7:42 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. 1/12
B. 1/6
C. 1/5
D. 1/3
E. 1/2
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by kajcha » Thu Sep 27, 2007 8:11 am
My ans 1/6

Total conditions = 4!

Fav conditions = 2! for white as any one can be planted at first or 4th position.
2! for red one for 2nd and 3rd positions

Prob = 2!*2!/4! = 1/6
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by samirpandeyit62 » Thu Sep 27, 2007 8:20 am
There are 4!/2!*2! ways i.e 6 ways of arranging the plants

out of which the two roses will be in middle only in one permutation

hence reqd p=1/6
Regards
Samir
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