SOLUTION: In a large city, the time taken to travel to work is normally distributed with a mean, and standard deviation. It is found that 4% of the population takes less than 5 minutes to ge

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Question 869820: In a large city, the time taken to travel to work is normally distributed with a mean, and standard deviation. It is found that 4% of the population takes less than 5 minutes to get to work, and 70% take less than 25 minutes.
Find the value of the mean and standard deviation.
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!


Hi

P(x < 5):  -1.75=  (5-m)/sd, m = 5 + 1.75sd  invNorm(.04) = -1.75

P(x < 25): -.6745 = (25-m)/sd,               invNorm(.25) = -.6745

           -.6745sd = 20-1.75sd

            1.0755sd = 20

                  sd = 18.6   and m = 5 + 32.543 = 37.543