18. An automobile manufacturer recommends oil change intervals of 3,000 miles. To compare actual intervals to the recommendation, the company randomly samples records of 50 oil changes at service facilities and obtains sample mean of 3,752 miles with a sample standard deviation of 638 miles. Determine whether the data provide sufficient evidence, at 5% level of significance, that the population mean interval between oil changes exceeds 3,000 miles.
18. An automobile manufacturer recommends oil change intervals of 3,000 miles. To compare actual intervals to the recommendation, the company randomly samples records of 50 oil changes at service facilities and obtains sample mean of 3,752 miles with a sample standard deviation of 638 miles. Determine whether the data provide sufficient evidence, at 5% level of significance, that the population mean interval between oil changes exceeds 3,000 miles.
MATLAB: An Introduction with Applications
6th Edition
ISBN:9781119256830
Author:Amos Gilat
Publisher:Amos Gilat
Chapter1: Starting With Matlab
Section: Chapter Questions
Problem 1P
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18 handwritten
Transcribed Image Text:Application:
n = 50, x=22.8,s=1.9
E
16. In the past the average length of an outgoing telephone call from a business
office has been 143 seconds. A manager wishes to check whether that average has
decreased after the introduction of policy changes. A sample of 100 telephone calls
produced a mean of 133 seconds, with a standard deviation of 35 seconds. Perform
the relevant test at 1% level of significance.
17. The average household size in a certain region several years ago was 3.14 persons.
A sociologist wishes to test, at 5% level of significance, whether it is different now.
Perform the test using the information collected by the sociologist: in a random
sample of 75 households, the average size was 2.98 persons, with sample standard
deviation 0.82 person.
18. An automobile manufacturer recommends oil change intervals of 3,000 miles. To
compare actual intervals to the recommendation, the company randomly samples
records of 50 oil changes at service facilities and obtains sample mean of 3,752
miles with a sample standard deviation of 638 miles. Determine whether the data
provide sufficient evidence, at 5% level of significance, that the population mean
interval between oil changes exceeds 3,000 miles.
of cervice that the mean time customers
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