Question

# As an aid for improving students' sleeping habits, nine students were randomly selected to attend a...

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?

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.

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