Test Prep 1 The managers of a popular test preparation company are developing two different preparation programs for an important exam that college students must take before applying to graduate...

Test Prep 1 The managers of a popular test preparation company are developing two different
preparation programs for an important exam that college students must take before applying to graduate
school. 20 students have volunteered to participate in one of the company’s prep programs. All of these
students have already taken the exam once, however they hope to improve their score after completing the
prep course. Half of the 20 students are randomly assigned to prep course “A”, while the remaining students are
assigned to prep course “B”. After the course, the students all take the exam again, and the tables below show
the difference (after – before) in each student’s exam scores.
Prep Course “A” 2 -1 12 2 9 4 8 0 1 7
Prep Course “B” 15 17 -3 4 27 5 11 13 -4 10
For the type of students who would volunteer for this company’s prep courses, construct and interpret a 95%
confidence interval for the difference in mean score improvement between prep course “A” and prep course “B”.

Test Prep 2 The same test preparation company is now working on a third preparation program for the
same graduate school entrance exam. From a large number of students that are signed up to take one of the
company’s prep courses, 10 students are randomly selected for this new course. All of these students have
already taken the exam once, however they hope to improve their score after completing the prep course. After
completing the course, the students all take the exam again, and the tables below show the “before” and “after”
scores for each of the ten students.
 Student
 A B C D E F G H I J
Before prep course 18 18 21 18 18 20 23 23 21 17
After prep course 24 25 33 29 33 36 34 36 34 27
For the type of students who would sign up for this company’s prep courses, construct and interpret a 95%
confidence interval for the mean difference in scores (after – before) on this graduate school entrance exam.