Hypothesis testing, inference of means A student in a class randomly selected 25 weekdays and tim

Theresa Archer

Theresa Archer

Answered question

2022-06-20

Hypothesis testing, inference of means
A student in a class randomly selected 25 weekdays and timed how long the 8am bus took to travel from home to school. His data gave an average travel time of 37 minutes and standard deviation of 2.5 minutes.
(a) Use the student's data to construct a 90% confidence interval for the true mean travel time from home to school for the 8am bus on weekdays. Also interpret the confidence interval in the context of this question.
(b) Do the student's data provided sufficient evidence that the true mean travel time is longer than 35 minutes? Carry out an appropriate hypothesis test at the 10% significance level.
I got no problem with (a) its 37+/- 1.711/2. However for (b), while the test statistic using the t-test gives me 4. the answer shows that the alpha value is 0.005 which makes no sense to me as I believe it should be 0.10 since its a one-tailed test.
Hope someone could find the problem here? Am I wrong or the answer is wrong?

Answer & Explanation

Hadley Cunningham

Hadley Cunningham

Beginner2022-06-21Added 20 answers

The hypothesis test will be:
H a = μ > 35
So, assuming μ = 35 calculate P ( X ¯ 35 .5 2 .5 = 4 ) So you need the tail area above 4 for a t-distributoin with 24 df. You will get a p-value ot .00026 < .1 so you have sufficient evidence to reject the hyopthesis of 35 minute mean.
Not sure what the .005 alpha was for.

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