Statistics
posted by Ivana .
Fire department response time is the length of time it takes a fire truck to arrive at the scene of a fire starting from the time the call was given to the truck. Response time for Gabble Fire Department follows a mound shaped and symmetric distribution. The response time has a mean of 8.5 minutes with a standard deviation of 1.8 minutes. If a random sample of 34 response times is taken and the mean response x is computed, find P(7 < x < 11)

A moundshaped symmetrical distribution sounds normal to me.
Z = (scoremean)/SEm
SEm = SD/√n
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability related to the Z scores.