Question

A certain test preparation course is designed to help students improve their scores on the LSAT exam. A mock exam is given at the beginning of the semester to determine the effectiveness of the course. The following measurements are the net change in 5 students scores on the exam after completing the course: 2, 14, 1, 2, -6 Use the data to construct a 90% confidence interval for the average change in a students score after completing the course. Assume the normal population. Step 1. Calculate the same mean. Step 2. Calculate the sample standard deviation. Step 3. Determine t-critical. Step 4. The 90% confidence interval is.

Answer 1

M = 2.6
t = 2.13
s_M = √(7.197²/5) = 3.22

μ = M ± t(s_M)
μ = 2.6 ± 2.13*3.22
μ = 2.6 ± 6.862

90% CI [-4.262, 9.462].