A consumer products testing group is evaluating two competing brands of tires, Brand 1 and Brand 2. Tread wear can vary considerably depending on the type of car, and the group is trying to eliminate this effect by installing the two brands on the same random sample of 10 cars. In particular, each car has one tire of each brand on its front wheels, with half of the cars chosen at random to have Brand 1 on the left front wheel, and the rest to have Brand 2 there. After all of the cars are driven over the standard test course for 20,000 miles, the amount of tread wear (in inches) is recorded, as shown in Table 1. Car Brand 1 Brand 2 Difference(Brand 1 - Brand 2) 1 0.362 0.293 0.069 2 0.363 0.335 0.028 3 0.220 0.168 0.052 4 0.364 0.297 0.067 5 0.399 0.395 0.004 6 0.351 0.338 0.013 7 0.386 0.377 0.009 8 0.276 0.251 0.025 9 0.206 0.228 -0.022 10 0.340 0.291 0.049 Table 1 Based on these data, can the consumer group conclude, at the 0.10 level of significance, that the mean tread wears of the brands differ? Answer this question by performing a hypothesis test regarding μd (which is μ with a letter "d" subscript), the population mean difference in tread wear for the two brands of tires. Assume that this population of differences (Brand 1 minus Brand 2) is normally distributed. Perform a two-tailed test. The null hypothesis: H0: The alternative hypothesis: H1: The type of test statistic: (Choose one)ZtChi squareF The value of the test statistic:(Round to at least three decimal places.) The two critical values at the 0.10 level of significance:(Round to at least three decimal places.) and At the 0.10 level, can the consumer group conclude that the mean tread wears of the brands differ? Yes No
A consumer products testing group is evaluating two competing brands of tires, Brand 1 and Brand 2. Tread wear can vary considerably depending on the type of car, and the group is trying to eliminate this effect by installing the two brands on the same random sample of
cars. In particular, each car has one tire of each brand on its front wheels, with half of the cars chosen at random to have Brand 1 on the left front wheel, and the rest to have Brand 2 there. After all of the cars are driven over the standard test course for
miles, the amount of tread wear (in inches) is recorded, as shown in Table 1.
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Table 1 |
Based on these data, can the consumer group conclude, at the
level of significance, that the mean tread wears of the brands differ? Answer this question by performing a hypothesis test regarding
(which is
with a letter "d" subscript), the population mean difference in tread wear for the two brands of tires. Assume that this population of differences (Brand 1 minus Brand 2) is
Perform a two-tailed test.
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