(C) 2008 GMAT Club - [t]m07#12[/t]

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(C) 2008 GMAT Club - [t]m07#12[/t]

by logitech » Fri Jan 16, 2009 6:01 pm
If Ben were to lose the championship, Mike would be the winner with a probability of 1/4, and Rob 1/3 If the probability of Ben being the winner is 1/7 , what is the probability that either Mike or Rob will win the championship?
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by sjd00d » Fri Jan 16, 2009 11:23 pm
Is it 37/84 by any chance? If so, let me know and i'll explain.

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by bluementor » Sat Jan 17, 2009 5:01 am
Probability of Mike winning = Ben looses AND Mike wins = (6/7)*(1/4)
Probability of Rob winning = Ben looses AND Rob wins = (6/7)*(1/3)

Prob(Mike or Rob to win) = Prob(Mike to win) OR Prob(Rob to win)
=(6/7)*(1/4) + (6/7)*(1/3)
=(6/7)*(1/4 + 1/3)
=(6/7)*(7/12)
=6/12
=1/2

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by logitech » Sat Jan 17, 2009 6:21 pm
bluementor wrote:Probability of Mike winning = Ben looses AND Mike wins = (6/7)*(1/4)
Probability of Rob winning = Ben looses AND Rob wins = (6/7)*(1/3)

Prob(Mike or Rob to win) = Prob(Mike to win) OR Prob(Rob to win)
=(6/7)*(1/4) + (6/7)*(1/3)
=(6/7)*(1/4 + 1/3)
=(6/7)*(7/12)
=6/12
=1/2

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You rock!
LGTCH
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"DON'T LET ANYONE STEAL YOUR DREAM!"