Suppose that the minimum and maximum ages for typical textbooks currently used in college courses are 2 and 8 years. Use the following rule of thumb to estimate the standard deviation.
Standard deviation =
Rule of thumb : Standard Deviation is about {Max-Min}/{4}
Find the size of the sample required to estimate the mean age of textbooks currently used in college courses. Assume that you want 94% confidence that the sample mean is within 0.1 year of the population mean.