17 Reading Japanese books. In the Reading in a Foreign Language (Apr. 2004) experiment to improve the Japanese reading comprehension levels of University of Hawaii students, 14 students participated in a 10-week extensive reading program in a second-semester Japanese course. The numbers of books read by each student and the student’s course grade are repeated in the following table and saved in the JAPANESE file.

a. Consider two populations of students who participate in the reading program prior to taking a second-semester Japanese course: those who earn an A grade and those who earn a B or C grade. Of interest is the difference in the mean number of books read by the two populations of students. Identify the parameter of interest in words and in symbols.

b. Form a 95% confidence interval for the target parameter identified in part a.

c. Give a practical interpretation of the confidence interval you formed in part b.

d. Compare the inference in part c with the inference you derived from stem-and-leaf plots.

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Number of Course Number of Course Books Grade Books Grade 53 42 40 40 39 AAABAAA 30 28 24 22 ABA C 21 B 20 B 16 B 34 34 Source: Hitosugi, C. I., and Day, R. R. "Extensive reading in Japa- nese." Reading in a Foreign Language, Vol. 16, No. 1, Apr. 2004 (Table 4). Reprinted with permissions from the National Foreign Language Resource Center, University of Hawaii.