Question

For a certain weekend, the weatherman predicts that it will rain with a 40% probability on Saturday and a 50% probability on Sunday. Assuming these probabilities are independent, what is the probability that it rains over the weekend (that is, on at least one of the days)? Express your answer as a percentage.

Answer 1

Answer:

70%

Step-by-step explanation:

The probability it rains on at least one of the days is:

P = P(Sat & not Sun) + P(Sun & not Sat) + P(Sat & Sun)

P = (0.40)(1−0.50) + (0.50)(1−0.40) + (0.40)(0.50)

P = 0.20 + 0.30 + 0.20

P = 0.70

Another way to look at it is 1 − the probability that it doesn't rain on either day.

P = 1 − P(not Sat & not Sun)

P = 1 − (1−0.40)(1−0.50)

P = 1 − 0.30

P = 0.70

There is a 70% probability that it will rain on at least one day.