Assume that it takes a college student an average of 5 minutes to find a parking spot in the main parking lot. Assume also that this time is normally distributed with a standard deviation of 2 minutes. What time is exceeded by approximately 75% of the college students when trying to find a parking spot in the main parking lot?

Question

Assume that it takes a college student an average of 5 minutes to find a parking spot in the main parking lot.  Assume also that this time is normally distributed with a standard deviation of 2 minutes. What time is exceeded by approximately 75% of the college students when trying to find a parking spot in the main parking lot?

Steve · Answer

Look up 0.7500 in your Z table. That is -.674 std from the mean.

Now scale and shift it for your problem:

5 - .675(2) = 3.65

A handy place to play around with this stuff is

http://davidmlane.com/hyperstat/z_table.html