8.3 An educational study was designed to investigate the effectiveness of a reading program of elementary age children. Each child was given a pretest and posttest.

Higher posttest scores would indicate reading improvement.

From a very large population, a random sample of scores for the pretest and posttest are as follows:

Child Pretest Score Posttest Score 1 40 48 2 36 42 3 32 4 38 36 5 43 6 33 38 7 35 45 Child 3 moved from the school district and did not take the posttest. Child 5 moved into the district after the start of the study and did not take the pretest.

Find a 95% confidence interval estimate of the mean improvement in the reading scores.

Application Exercises