A report states that the cost of repairing a hybrid vehicle is falling even while typical repairs
Question:
A report states that the cost of repairing a hybrid vehicle is falling even while typical repairs on conventional vehicles are getting more expensive. The most common hybrid repair, replacing the hybrid inverter assembly, had a mean repair cost of $3,9273,927 in 2012. Industry experts suspect that the cost will continue to decrease given the increase in the number of technicians who have gained expertise on fixing gas-electric engines in recent months. Suppose a sample of 100 hybrid inverter assembly repairs completed in the last month was selected. The sample means repair cost was $3,7603,760 with the sample standard deviation of $600.
Complete parts (a) and (b) below.a. Is there evidence that the population means cost is less than $3,9273,927? (Use a 0.10 level of significance.)
State the null and alternative hypotheses.
Find the test statistic for this hypothesis test.
t= (Round to two decimal places as needed.)
The critical value(s) for the test statistic is(are)
nothing. (Round to two decimal places as needed. Use a comma to separate answers as needed.)
Is there sufficient evidence to reject the null hypothesis using α=0.100.10?
A. Do not reject the null hypothesis. There is insufficient evidence at the 0.10 level of significance that the population mean cost is greater than $3,9273,927.
B. Reject the null hypothesis. There is sufficient evidence at the 0.10 level of significance that the population mean cost is greater than $3,9273,927.
C. Do not reject the null hypothesis. There is insufficient evidence at the 0.10 level of significance that the population mean cost is less than $3,9273,927.
D. Reject the null hypothesis. There is sufficient evidence at the 0.10 level of significance that the population mean cost is less than $3, 9273,927.
b. Determine the p-value and interpret its meaning.
The p-value is (Round to three decimal places as needed.)
What does this p-value mean given the results of part (a)?
A.The p-value is the probability that the actual mean cost is$3,7603,760 or less.
B.The p-value is the probability that the actual mean cost is more than $3,7603,760.
C.The p-value is the probability of getting a sample mean cost of $3,7603,760 or less if the actual mean cost is$3,9273,927.
D.The p-value is the probability that the actual mean cost is$3,9273,927 or less given the sample mean cost is$3,7603,760.
Business Statistics A First Course
ISBN: 978-0321979018
7th edition
Authors: David M. Levine, Kathryn A. Szabat, David F. Stephan