SOLUTION: Bob lives in town A but works in Town B. He knows that the time it takes him to commute from home to work on any morning is normally distributed with mean 56 minutes and standard d

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Question 1046472: Bob lives in town A but works in Town B. He knows that the time it takes him to commute from home to work on any morning is normally distributed with mean 56 minutes and standard deviation 6 minutes.
If he is expected to be in work for the latest at 8 00 am, what time should he leave home in order to be 95% sure that he arrives by 8 00 am.
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
Using the empirical rule, 95% of the time is within 2 sd s on either side of the mean.
The mean is 56 minutes, and 2 sd s are 12 minutes.
Therefore, the maximum time is 56+2 sd s or 56 min+12 min or 68 minutes.
If he leaves at 6:52 am, he will be within the commute time + 2 sd s, which is the maximum time it will take him. Any other time, he will arrive before 8 am.
6:52 am ANSWER.