QNT/ 275-Gamma Corporation is considering the installation
Gamma Corporation is considering the installation of governors on cars driven by its sales staff. These devices would limit the car speeds to a preset level, which is
expected to improve fuel economy. The company is planning to test several cars for fuel consumption without governors for 1 week. Then governors would be installed in
the same cars, and fuel consumption will be monitored for another week. Gamma Corporation wants to estimate the mean difference in fuel consumption with a margin of
error of estimate of 2 mpg with a 90% confidence level. Assume that the differences in fuel consumption are normally distributed and that previous studies suggest that
an estimate of sd=3sd=3 mpg is reasonable. How many cars should be tested? (Note that the critical value of tt will depend on nn, so it will be necessary to use trial
and error.)
