SOLUTION: As of April 20,2010, a random sample of 50 Major League pitchers has an earned run average (ERA) of 3.91 with standard deviation of 1.89. The distribution of all Major League Baseb

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Question 868952: As of April 20,2010, a random sample of 50 Major League pitchers has an earned run average (ERA) of 3.91 with standard deviation of 1.89. The distribution of all Major League Baseball pitchers is known to be approximately normal. Calculate the 90% confidence interval for the mean ERA for the population of Major League Baseball pitchers.
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!


Hi

ME = 1.645%281.89%2Fsqrt%2850%29%29 = .44 (nearest one-hundredth)

CI:  3.91-ME < u <  3.91 + ME

CI:  3.91-.44 < u <  3.91 + .44

CI = (3.47, 4.35)