Carcass wrote:
The probability of rain showers in Barcelona on any given day is 0.4. What is the probability that it will rain on exactly one out of three straight days in Barcelona?
A. 0.144
B. 0.072
C. 0.432
D. 0.72
E. 0.288
Key concept: P(Event A happening) = 1 - P(Event A not happening)If P(rain) = 0.4, then P(no rain) = 1 - 0.4 = 0.6
P(rain exactly once) = P(rain day 1
AND no rain day 2
AND no rain day 3
OR no rain day 1
AND rain day 2
AND no rain day 3
OR no rain day 1
AND no rain day 2
AND rain day 3)
= (0.4
x 0.6
x 0.6)
+ (0.6
x 0.4
x 0.6)
+ (0.6
x 0.6
x 0.4)
= 0.096
+ 0.096
+ 0.096
= 0.288
Answer: E