Refer to Exercise 8.47. In addition to tests involving biology concepts, students were also tested on process skills. The results of pretest and posttest scores, published in The American Biology Teacher, are given below.

a. Find a 95% confidence interval for the mean score on process skills for the posttest for all BACC classes.
b. Find a 95% confidence interval for the mean score on process skills for the posttest for all traditional classes.
c. Find a 95% confidence interval for the difference in mean scores on process skills for the posttest BACC classes and the posttest traditional classes.
d. Does the confidence interval in c provide evidence that there is a real difference in the mean process skills scores between posttest BACC and traditional class scores? Explain.

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Sample Standard Mean Size Deviation Pretest AlI BACC Classes 10.52 395 Pretest All Traditional Posttest: All BACC Classes 14.06 376 Posstest All Traditional 12.96 308 4.79 11.97 379 5.39 5.65 5.93