Question

As an aid for improving students' sleeping habits, nine students were randomly selected to attend a seminar on the importance of sleep in life. The table below shows the number of hours each student slept per week before the seminar.

Students	1	2	3	4	5	6	7	8	9
Before	9	12	6	15	3	18	10	13	7
After	9	17	9	20	2	21	15	22	6

a. Construct a 90% confidence interval for the difference of mean number of study hours before and after attending the seminar and INTERPRET

b. At 10% level of significance, did attending the seminar increase the number of hours the students studied per week?

Would gladly appreciate your help! Thank you so much! :)

Answer 1

Ans:

Students	1	2	3	4	5	6	7	8	9
Before	9	12	6	15	3	18	10	13	7
After	9	17	9	20	2	21	15	22	6
difference(d)	0	5	3	5	-1	3	5	9	-1
mean(d)=	3.111
std. dev	3.333

a)df=9-1=8

critical t value=tinv(0.1,8)=1.860

90% confidence interval for mean difference

=3.111+/-1.860*(3.333/sqrt(9))

=3.111+/-2.067

=(1.044, 5.178)

b)As both limits of above confidence interval are positive,we can conclude that attending the seminar increase the number of hours the students studied per week.