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by maihuna » Tue Mar 15, 2011 12:11 pm
A certain board game consists of a circular path of 100 spaces
colored in a repeating pattern of black, yellow, green, red, and
blue. What is the probability that, in a random selection of seven
consecutive spaces, 2 of the spaces are blue?
(A) 2
25
(B) 1
7
(C) 1
5
(D) 2
7
(E) 2
5
Charged up again to beat the beast :)
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by force5 » Tue Mar 15, 2011 2:07 pm
IMO- 2/5 (E)... there can be many ways to do this question. although we need 7 spaces. but there can be only 5 ways to start counting. since there are only 5 different numbers (so we get restricted). besides in only 2 ways will blue get repeated again. (start counting with red and start counting with blue)hence reqd prob is 2/5..
we can also do the question by making cases.
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