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by maihuna » Fri Aug 14, 2009 1:18 am
In a relay race there are five teams A, B, C, D and E. What is the probability that A, B and C are first three to finish (in any order) (Assume that all finishing orders are equally likely)

1/60
1/40
1/30
1/20
1/10
Charged up again to beat the beast :)
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by tohellandback » Fri Aug 14, 2009 1:51 am
IMO E
Total number of ways the race ends=5!
for A,B,C to finish first, fix them in the sequence like

A B C D E

D,E can be arranged in 2ways
ABC can be arranges in 3! ways
prob= 2*3!/5!
=1/10
The powers of two are bloody impolite!!
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by Naruto » Fri Aug 14, 2009 1:58 am
Ans. 1/10

There are 5C3=10 ways to choose a three teams out of five. Choosing ABC is one way among them (particular case) therefore the probability is 1/10

(This is because the order of the teams that finish 1st,2nd,3rd doesnt count)
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