申論題

8.At the beginning of the schoo! year, the mean score of a group of 49 sixth-grade students on an achievement test in reading was 70 with an unbiased sampie variance of 36. At the end of the school year, the mean score on an equivalent form of the same test was 74 with an unbiased sample variance of 25. The correlation between scores made on the initial and final testing was 0.6. To test whether the mean scores on these two exams are significantly different based on the Student t-test, the figure of the test statistic is equal to___________.