SOLUTION: A study of 60 professors showed that the time they spent on the average in creating test questions was 20.0 minutes per question. The standard deviation of the population is 1. Whi

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Question 1039846: A study of 60 professors showed that the time they spent on the average in creating test questions was 20.0 minutes per question. The standard deviation of the population is 1. Which of the following is the 98% confidence interval for the average number of minutes it takes to create a test question?
A.
(17.67, 22.33)
B.
(19.49, 20.51)
C.
(19.70, 20.30)
D.
(19.79, 20.21)
Answer by robertb(5830) About Me  (Show Source):
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C. (19.70, 20.30)

(20.0+-+2.326%2A%281%2Fsqrt%2860%29%29, 20.0+%2B+2.326%2A%281%2Fsqrt%2860%29%29)
=(19.70, 20.30).