This exercise is based on the following information, gathered from student testing of a statistical software package called MODSTAT. Students were asked to complete certain tasks using the software, without any instructions. The results were as follows. (Assume that the time for each task is normally distributed.) It can be shown that if X and Y are independent normal random variables with means  and

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TaskMean Time(minutes)StandardDeviationTask 1: Descriptive Analysis of Data11.45.0Task 2: Standardizing Scores11.99.0Task 3: Poisson Probability Table7.54.1Task 4: Areas Under Normal Curve9.55.9?

A. 0.3382
B. ?0.6638
C. ?0.6764
D. ?0.3372
E. ?0.6628


Answer: D

Mathematics

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