According to a leasing firm's reports, the mean number of miles driven annually in its leased cars is 13,000 miles with a standard deviation of 3320 miles. The company recently starting using new contracts which require customers to have the cars serviced at their own expense. The company's owner believes the mean number of miles driven annually under the new contracts, μ, is less than 13,000 miles. He takes a random sample of 46 cars under the new contracts. The cars in the sample had a mean of 11,671 annual miles driven. Assume that the population is normally distributed. Is there support for the claim, at the 0.01 level of significance, that the population mean number of miles driven annually by cars under the new contracts, is less than 13,000 miles? Assume that the population standard deviation of miles driven annually was not affected by the change to the contracts.Perform a one-tailed test. Then complete the parts below.Carry your intermediate computations to three or more decimal places, and round your responses as specified below.

MATLAB: An Introduction with Applications
6th Edition
ISBN:9781119256830
Author:Amos Gilat
Publisher:Amos Gilat
Chapter1: Starting With Matlab
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According to a leasing firm's reports, the mean number of miles driven annually in its leased cars is 13,000 miles with a standard deviation of 3320 miles. The company recently starting using new contracts which require customers to have the cars serviced at their own expense. The company's owner believes the mean number of miles driven annually under the new contracts, μ, is less than 13,000 miles. He takes a random sample of 46 cars under the new contracts. The cars in the sample had a mean of 11,671 annual miles driven. Assume that the population is normally distributed. Is there support for the claim, at the 0.01 level of significance, that the population mean number of miles driven annually by cars under the new contracts, is less than 13,000 miles? Assume that the population standard deviation of miles driven annually was not affected by the change to the contracts.Perform a one-tailed test. Then complete the parts below.Carry your intermediate computations to three or more decimal places, and round your responses as specified below.

 

 

A marriage counselor has traditionally seen that the proportion p of all married couples for whom her communication program can prevent divorce is 80%.
After making some recent changes, the marriage counselor now claims that her program can prevent divorce in more than 80% of married couples. In a
random sample of 215 married couples who completed her program, 180 of them stayed together. Based on this sample, is there enough evidence to support
the marriage counselor's claim at the 0.05 level of significance?
Perform a one-tailed test. Then complete the parts below.
Carry your intermediate computations to three or more decimal places. (If necessary, consult a list of formulas.)
Transcribed Image Text:A marriage counselor has traditionally seen that the proportion p of all married couples for whom her communication program can prevent divorce is 80%. After making some recent changes, the marriage counselor now claims that her program can prevent divorce in more than 80% of married couples. In a random sample of 215 married couples who completed her program, 180 of them stayed together. Based on this sample, is there enough evidence to support the marriage counselor's claim at the 0.05 level of significance? Perform a one-tailed test. Then complete the parts below. Carry your intermediate computations to three or more decimal places. (If necessary, consult a list of formulas.)
(c) Finding the value of the test statistic
The value of this test statistic is the z-value corresponding to the sample proportion under the assumption that His true. Here is i
P-P
p(1-p)
n
36
43
0.80
0.80(1-0.80)
215
1.364
Transcribed Image Text:(c) Finding the value of the test statistic The value of this test statistic is the z-value corresponding to the sample proportion under the assumption that His true. Here is i P-P p(1-p) n 36 43 0.80 0.80(1-0.80) 215 1.364
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