Question 1161221: An executive at Westinghouse drives from her home in the suburbs near Pittsburgh to her office. The driving times are normally distributed with a mean of 35 minutes and a standard deviation of 8 minutes.
A. What percent of the days will it take her 30 minutes OR LESS to drive to work?
B. What percent of the days will it take for 40 minutes OR MORE to drive to work?
C. If there are delays, how long will the longest 10 percent of the trips take?
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! fewer than 30 minutes is a z<(30-35)/8 or z<-5/8. prob is 0.2660 or 26.6%
greater than 40 minutes is the same probability since the function is symmetrical 26.6%
The longest 10 per cent of the trips will take (need z for 90th percentile, which is 1.282).
41.4 minutes or longer.
Can use 2 VARS 3 invnorm (.900,35,5) ENTER
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