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berrysryummy
11-02-2015, 12:41 AM
Here is the problem:

Megan drives to work each morning. Her commute time is normally distributed with mean 30 minutes and standard deviation 4 minutes. Her workday begins at 9:00AM. At what time should she leave for work so that the probability she is on time is 95%?

I know the value of x bar, sigma, and z of alpha over 2, but I have no idea where to get n. Am I using the completely wrong formula?

x bar = 30
sigma=4
z of alpha over 2= 1.95996


I'm using x bar +/- z* alpha times sigma over the square root of n.

maddy23
11-04-2015, 06:53 PM
did you ever figure out how to do this? this is my math problem this week and i'm stuck. thanks

maddy23
11-04-2015, 06:55 PM
did you ever figure out how to do this? This is my math problem this week and i'm stuck. thanks