If the probability of rain on any given day in City X is 60%, what is probability that it rains on exactly 3 days in a 4 day period?  Choose the correct option
A) 16/25 B) 86/125 C) 96/125 D) 216/625 E) 336/625
One possible way is rain-rain-rain-no rain.   The probability of this is 3/5*3/5*3/5*2/5 = 54/625   The number of possible ways is 4C3 = 4, so we multiply this by 4.   P(rain on exactly 3 days) = 4*54/625 = 216/625   The answer is 216/625.
<result>D</result>
If the probability of rain on any given day in City X is 60%, what is probability that it rains on exactly 3 days in a 4 day period?