Question

Researchers have collected data from a random sample of six students on the number of hours spent studying for an exam and the grade received on the exam as given in Table 6.5.

Table 6.5

Observation	Grade	Number of Hours Studying
1	85	8
2	73	10
3	95	13
4	77	5
5	68	2
6	95	12

f) Find and interpret a 99% confidence interval for the mean grade of all individuals who spend 10 hours studying.

Answer 1

Using Minitab software, we get the following regression equation :(Stat -> Regression -> Regression)

Grade = 63.73 + 2.213 Number of hours studying

Then, again using Minitab software, we get the following regression equation :(Stat -> Regression -> Predict), we get the following output :

a 99% confidence interval for the mean grade of all individuals who spend 10 hours studying

=(70.9678, 100.741)

Interpretation : The true mean grade of all individuals who spend 10 hours studying will lie between (70.9678, 100.741) with probability 0.99