Problem Solving

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

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