The average cost of a gallon of unleaded gasoline in Greater Cincinnati was
reported to be \(\$ 2.41(\text {The Cincinnati Enquirer, } \text { February }
3,2006\) ). During periods of rapidly changing prices, the newspaper samples
service stations and prepares reports on gasoline prices frequently. Assume
the standard deviation is \(\$ .15\) for the price of a gallon of unleaded
regular gasoline, and recommend the appropriate sample size for the newspaper
to use if it wishes to report a margin of error at \(95 \%\) confidence.
a. Suppose the desired margin of error is \(\$ .07\)
b. Suppose the desired margin of error is \(\$ .05\)
c. Suppose the desired margin of error is \(\$ .03\)