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! :)
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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