In order to test the claim that the mean number of study hours of UC3M undergraduate students is different from 15 hours per week, a survey was conducted on a random sample of students.  The average number of study hours in the sample was 13.8 hours per week. For a hypothesis test in this context, with a significance level of 0.1:

Select one:

a.
The true mean number of study hours will be assumed to be different from 15 unless the sample contains enough evidence, at a 10% significance level, that this is false.



b.
The null hypothesis would be rejected if the 90% confidence interval for the true mean number of hours doesn’t contain 13.8.



c.
The value of the true mean of study hours under the null hypothesis is 15.



d.
The null hypothesis is that the true mean number of hours is different from 15.