HELP!!!! Find the probability that it takes at least 9 minutes to find a parking space. (Round your answer to four decimal places.)

Question

The length of time it takes to find a parking space at 9 A.M. follows a normal distribution with a mean of 6 minutes and a standard deviation of 3 minutes.

Find the probability that it takes at least 9 minutes to find a parking space. (Round your answer to four decimal places.)

Answer 1

x = mean time, normal distributed with mean = 6 and SD = 3

want to find P(x > 9)

convert x to standard normal distribution of mean = 0 and SD = 1 using z = (x - mean)/SD = (x - 6)/3

so P(x > 9) = P(z > (9-6)/3) = P(z > 1) = P(z < - 1) = 0.1587