Referring to Exercise 8.12b (page 299), assume that the population standard deviation equals .66. How large a sample of late replacement buyers is needed to make us?
In exercise Suppose that a random sample of 500 late replacement buyers yields a mean number of dealers visited equal to 4.3, and assume that the population standard deviation equals .66. Calculate a 99 percent confidence interval for the population mean number of dealers visited by all late replacement buyers.
a. 99 percent confident that the sample mean number of dealers visited, is within a margin of error of .04 of m, the population mean number of dealers visited?
b. 99.73 percent confident that is within a margin of error of .05 of μ?