A federal regulatory agency is investigating an advertised claim that a certain device can increase the gasoline mileage of cars (mpg). Ten such devices are purchased and installed in cars belonging to the agency. Gasoline mileage for each of the cars is recorded both before and after installation. The data are recorded here.
Place 90% confidence intervals on the average mpg for both the before and the after phases of the study. Interpret these intervals. Does it appear that the device will significantly increase the average mileage of cars?
Answer to relevant QuestionsRefer to Exercise 5.74. In exercise a. The cars in the study appear to have grossly different mileages before the devices were installed. Use the change data to test whether there has been a significant gain in mileage ...Refer to Exercise 6.9. a. Based on the values of the sample mean and sample standard deviation for magnesium, provide a reason why the distribution of magnesium does not have a normal distribution. b. Are the inferences ...A cable TV company was interested in making its operation more efficient by cutting down on the distance between service calls while still maintaining at least the same level of service quality. A treatment group of 18 ...A potential criticism of analyzing these data as if they were two independent samples is that the measurements taken in 1996 were taken at the same sites as the measurements taken in 1982. Thus, there is the possibility that ...Use the level and power values for the paired t test and Wilcoxon signed-rank test given in Table 6.18 to answer the following questions: a. Suppose a level .05 test is to be applied to a paired data set that has ...
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