Question

Thirty randomly selected students took the calculus final. If the sample mean was 77 and the standard deviation was 11.9, construct a 99% confidence interval for the mean score of all students. Round your answer in 2 decimal places

Answer 1

z @ 99.0% = 2.5758

Since we know that

Required confidence interval = (77.0-2.5758(2.1726), 77.0+2.5758(2.1726))
Required confidence interval = (77.0 - 5.5963, 77.0 + 5.5963)
Required confidence interval = (71.40, 82.60)

Interpretion: We are 99.0% confident that the true mean of the population lie between the interval 71.40 and 82.60.

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