Question

The average fuel economy of a sample of 79 Japanese cars was 30.5 mpg with a standard deviation 6.1 mpg. Do these data present evidence that the average fuel economy of all Japanese cars is higher than the corresponding US average of 20.1 mpg? Report and appropriate hypothesis test, write out all the steps we went over in class, and use a 1% significance level |(1) We are testing [Select] (2) Ho: The average fuel economy [Select [Select] (3) Ha: The average fuel economy is a SRS, and we assume that the population (4) We assume that the [Select ] has no outliers distribution of [Select] [Select ] [Select] (5) We will do a procedure because u[Select [Select ] [Select then due to sampling variation (6) If the average fuel economy is [Select] [Select ] of all possible sample mean fuel economies are expected to be alone [Select ] when the sample consist of 79 cars each. This [Select ] suggest that the average fuel economy of all Japanese cars [Select If we are making an error here, what type of error would it be? [Select ]

Answer 1

Solution:-

1) We are testing population mean.

2) H₀ : The average fuel economy of all Japanese car is 20.1 mpg.

3) H_A : The average fuel economy of all Japanese car is greater than 20.1 mpg

4) We assume that the sample is SRS and we assume that the population distribution of Japanese cars has no outliers.

5)

We will do a one-sample z-test procedure, because the sample size is large enough.

20.1

/n

30.5 20.1 6.1 V79

z = 15.15

p-value is less than 0.0001.

6) If the average fuel economy is 20.1, then due to the sampling error alone 0.00 of all possible sample mean fuel economies are expected to be equal to or greater than 30.5 mpg, when the sample consists of 79 cars each.

This strongly suggests that the average economy of all the Japanese cars is greater than 30.5.

If we are making an error here, we might have committed type I error.