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?
0.008
0.128
0.488
0.512
0.640
no rain on first day, no rain on second day, rain on third day (Monday).
so which is 1-0.2=0.8 is the possibility of no rain.
0.8*0.8*0.2=0.128
指定第三天下雨,因此没必要乘3
0.8*0.8*0.2
0.8*0.8*0.2