SOLUTION: An executive drives from his home in Portmore to his office at the Bank of Jamaica. The driving times are normally distributed with a mean of 34 minutes and a standard deviation

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Question 1109928: An executive drives from his home in Portmore to his office at the Bank of Jamaica. The
driving times are normally distributed with a mean of 34 minutes and a standard
deviation of 7 minutes.
(a) In what percent of the days will it take him 25 minutes or less to drive to work?
(b) Some days there will be accidents or other delays, so the trip will take longer than
usual. What is the minimum time taken to get to work for the longest 10% of the
trips?

Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
z=(x-mean)/sd
-(25-34)/7=-9/7 or -1.29
probability that z < -1.29 is 0.0985, or 9.85%
For the longest 10%, z>=+1.282
1.282=(x-34)/7
8.974=x-34
x=43.0 minutes is minimum time