The Speedy Oil Change Company advertised 18-minute wait for an oil change. A sample of 24 oil changes showed a mean time of 18.8 minutes and from previous studies it is known that the population standard deviation is 2.9 minutes. At the 5% level of significance, is there evidence that the mean time for an oil change is different from 18 minutes? Assume the data is normally distributed. Perform the following steps of hypotheses testing and draw a conclusion.
Question 9 options:
10. The Speedy Oil Change Company advertised 18-minute wait for an oil change. A sample of 24 oil changes showed a mean time of 18.8 minutes and from previous studies it is known that the population standard deviation is 2.9 minutes. At the 5% level of significance, is there evidence that the mean time for an oil change is different from 18 minutes? Assume the data is normally distributed. Perform the following steps of hypotheses testing and draw a conclusion.
a.1) State the hypotheses.
Fill the blanks by these words: equal to, not equal to, greater than, less than, greater or equal to, less than or equal to,
Separate your answers with comma.
Ho:μ is ...? minutes
Ha: μ is ...? minutes
a.2) Which distribution should be used?
Fill the blanks by these words:z or t
...? table.
a.3) What type of test it will be?
Fill the blanks by these words:left, right or two.
...? tailed test.
b) Find the critical value(s).
If there are more than one critical value, separate them with comma in between.
c) Compute the test statistics.
Round to three decimal places.
d) Make the decision.
Fill the blanks with these words:Critical or acceptance and reject or fail to reject.Separate your answers with comma in between.
The test statistics falls under the...? region
Therefore,...? null hypothesis.
e) Summarize the results.
Fill the blank with eitherenough ornot enough words.
Therefore, this is ...?evidence to support the claim that the mean time for an oil change is different from 18 minutes.