Grear Tire Company has produced a new tire with an estimated mean lifetime mileage of 37,500 miles. Management also believes that the standard deviation is 6,000 miles and that tire mileage is normally distributed. Use a worksheet to simulate the miles obtained for a sample of 500 tires.
(a) Use the Excel COUNTIF function to determine the number of tires that last longer than 40,000 miles. What is your estimate of the percentage of tires that will exceed 40,000 miles?
(b) Use COUNTIF to find the number of tires that obtain mileage less than 32,000 miles. Then find the number with less than 30,000 miles and the number with less than 28,000 miles.
Subject in a study of body mass index (BMI) included a sample of 40 men who claimed to engage in a variety of sports activites (the multisport group). The mean BMI for these men was 22.41 with a standard deviation of 1.27.A second group of 24 male rugby players had a mean BMI of 27.75 with a standard deviation of 2.64. Is there a sufficient evidence for one to conclude that, in general, rugby players have higher BMI than multisport men? use alpha = 0.05 Make sure to write the appropreate null and alternate hypotheses, then test them.