Here is the problem:
(A) Select a random sample of 30 student from our population (we have a data entry to get the sample from). At the 0.05 level of significance is there evidence that the average travel time is greater than 45 minutes?
(B) What assumptions must hold in order to perform the test in (A)?
(C) Evaluate the assumption in (B) through a graphical approach. Are the results valid? Discuss.
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Part (A) is the one I need the most help with,but more help is always welcome
I'm not sure which formula to use, am I using the null hypothesis? Z-test? I'm SO confused. What is the procedure for solving this?
THANKS SO MUCH IN ADVANCE FOR ANY HELP!
First, relax
1) With your sample of 30, calculate the mean (average) travel time and the standard deviation. (I presume you know how to do these calculations).
2) Calculate the number of standard deviations that 45 minutes is away from the mean. That is X=(mean-45)/SD
(mean and SD are the estimated mean and standard deviation from step 1.
3) null hypothesis, mean travel time is not greater than 45 minutes. Your test is a 1-tailed test. So, find a cumulative normal distribution table (probably in your stats book) Find the Alpha associated with the 95 percentile. In my book, Alpha=1.645
4) If your X in step 2 is greater than 1.645, then reject the null hypothesis: travel time IS greater than 45 minutes. If less, then do not reject the null hypothesis.
I hope this helps