1 Appliance Magazine provided estimates of the life expectancy of electrical appliances. A sample of 10 VCRs shows the useful life in years. 6.5, 8.0, 6.2, 7.4, 7.0, 8.4, 9.5, 4.6, 5.0, 7.4 1. What is the point estimate of the population mean life expectancy for VCR's? 2. What is the point estimate of the population standard deviation for life expectancy of VCR's? n Total Average x x x x ( x x )2 d.f. 2 s s Problem 2 A population has a mean of 300 gallons with a standard deviation of 50. Suppose a single random sample of size 100 is selected. 1. What is the probability that the sample mean will be within + 5 of the population mean? What do you know? = _______ x = _______ = _______ s = _______ n = _______ N = _______ Show your work. Draw your findings. Make sure you label for both the x and z values on the horizontal axis. Problem 3 The American Association of Advertising Agencies records data on length of nonprogramming time on half hour prime time television shows. Representative data in minutes for a sample of 20 prime time shows on major networks at 8:30 P.M. follows. Show your work n Total Average x x x x ( x x )2 d.f. 2 s s Problem 3 Continued. What do you know? x s n N CC = = = = = = = = = Provide a point estimate and a 95% confidence interval for the mean number of nonprogram minutes on half hour prime time television shows at 8:30 P.M. Assume the time has a normal distribution. What table will you use? ______________ Why will you use this table? _________________________________________ Show your work. State your formula first, then solve the formula with what you know. Draw your findings. Make sure you label for both the x and z values on the horizontal axis. Problem 4 Annual starting salaries for college graduates with business administration degrees are believed to have a standard deviation of approximately $2,000. Assume that a 95% confidence interval estimate of the new annual starting salary is desired. How large a sample should be taken if we do not want to exceed $500? What do you know? x s n N CC = = = = = = = = = Show your work What sample size do we need? ____________________