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Unformatted text preview: STAT 1000 Assignment 6 (Not to be handed in ) 1. An auto manufacturer makes a type of car that is known to have an average mileage of 31.5 mpg on the highway and standard deviation 5.6 mpg. They want to put a new engine in this type of car, and they want to see if this increases the average mpg. They select a random sample of 20 cars with the new engine, and those cars have an average mileage of 32.8 mpg, with standard deviation 6.3 mpg. (a) Construct a 99% confidence interval for the true mean mileage of all cars with the new engine. (b) We would like to conduct a hypothesis test to determine whether there is evidence that the smaller engine increases the average mileage for the cars. If we want very strong evidence that the smaller engine increases the average mileage, should we use a high or low level of significance? Explain. (c) Conduct an appropriate hypothesis test, at the 1% level of significance, to determine whether there is evidence that the smaller engine increases the average mileage for the cars. (d) Could you have used the confidence interval in (a) to conduct the test in (c)? Why or why not? If you could have used the confidence interval, explain what your conclusion would be, and why.conclusion would be, and why....
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 Spring '12
 XU
 Statistics, Standard Deviation, appropriate hypothesis test

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