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probability

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by ketkoag » Sat May 09, 2009 10:05 am
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?
A. 0.008
B. 0.128
C. 0.488
D. 0.512
E. 0.640
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Source: — Problem Solving |

by scoobydooby » Sat May 09, 2009 11:01 am
if M returns on Monday eod, it must have rained first on monday in the period of vacation from saturday to monday.

prob( M returns on Monday end): p(no rain on Sat)*p(no rain on Sunday)*p(rain on monday)

=>0.8*0.8*0.2
=>0.128

B
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