MSCI 3710 Two sample t-test (Chapter 9): Sample Exam Problem 5 Note: The following problem is taken from the Mid-term Exam in Fall 2002, questions 6-7. The CEO of Mean Green Cab Company believes there is a difference between the durability of two brands of tires, Minus and Rub . The CEO decides to test her belief by running an experiment. To conduct the experiment, her R & D department uses a machine with a metallic device to wear down the tires and records the tread depth on a random sample of 10 tires of each brand after new tires are spun for an equivalent of 10,000 miles. Excel output for the test, on the sample data, conducted at the 5% significance level is shown in the tables below. t-Test: Two-Sample Assuming Equal Variances Rub Minus Mean 0.2415 0.2538 Variance 0.0004 0.0009 Observations 10 10 Pooled Variance 0.0007 Hypothesized Mean Difference0 df 18 t Stat-1.0183 P(T<=t) one-tail 0.161 t Critical one-tail 1.734 P(T<=t) two-tail 0.322 t Critical two-tail 2.101 1. To test the claim that there is a difference between the durability of
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