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GMATFocus Q2 - probability

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by frizo » Wed Feb 11, 2009 9:57 pm
On saturday morning, malachi will begin a camping vacation and he will return home at the end of the first day on which it rains. If on the first three days of the vacation the probability of rain on each day is 0.2, what is the probability that malachi will return home at the end of the day on the following monday?
.008
.128
.488
.512
.640
B
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Source: — Problem Solving |

by Bidisha800 » Wed Feb 11, 2009 10:20 pm
probability = no rain X no rain X rain

=0.8*0.8*0.2
=0.128
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Re: GMATFocus Q2 - probability

by x2suresh » Wed Feb 11, 2009 10:21 pm
frizo wrote:On saturday morning, malachi will begin a camping vacation and he will return home at the end of the first day on which it rains. If on the first three days of the vacation the probability of rain on each day is 0.2, what is the probability that malachi will return home at the end of the day on the following monday?
.008
.128
.488
.512
.640
B
= (prob that Saturday No rain)*(Prob that Sunday No rain)* Prob that Monday rain

= 0.8*0.8*0.2 = 0.128
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by ven4gmat » Thu Feb 12, 2009 1:58 am
In order to return home on Monday, it should not rain on saturday, sunday and it should rain on monday.

So the probability is 0.8x0.8x0.2 = 0.128
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