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1. In an investigation of educational quality in Kansas City elementary schools you

notice that "bright" students appear to be taller and weigh more than "slow" students. You begin to wonder if there is a relationship between academic performance and nutrition. Government reports have hypothesized that malnutrition can adversely affect the learning process and lower student achievement.

As a result of your own observations and the government reports, you believe that malnourished students will tend to do poorly in school, and wish to test your hypothesis. Since you have no data on what students eat, you decide to test your belief indirectly using students' weights. In a large elementary school, you ask teachers to identify "bright" and "slow" students. You then check the students' records to obtain their weights, which are given in the table below.

Use the difference-of-means test to determine whether the mean weight of "bright" students is significantly higher than the mean weight of "slow" students. Presume that the weights of students in each group are normally distributed and that you have equal population variances. Also assume that α = .05.



  "bright"                                                     "slow"




105                                                    76


 93                                                      85       


 88                                                      94


 96                                                      90


100                                                    79


101                                                    83


 87                                                      68


 95                                                      89


 99                                                      94


102                                                  101


 87                                                      77


 71                                                      94


103                                                    87


 83                                                      83


 91                                                    103


 96                                                      72

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