Posted by Shannon on .
**I don't want the answer, I want to know how to set the problem up and the formula that I need to use. I am online with a tutor right now, and they can't help me. :(
The average price of a gallon of unleaded regular gasoline was reported to be $2.34 in northern Kentucky (The Cincinnati Enquirer, January 21, 2006). Use this price as the population mean, and assume the population standard deviation is $.20.
1. What is the probability that the mean price for a sample of 30 service stations is within $.03 of the population mean (to 4 decimals)?

Satistics 
PsyDAG,
Z = (scoremean)/standard error of the mean (SEm)
Scores = (mean.03) and (mean+.03)
SEm = SD/√n
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion related to the Z scores.