In: Statistics and Probability
Use Excel to answer. A college admission officer for an MBA program determines that historically candidates have undergraduate grade averages that are normally distributed with standard deviation of .45. A random sample of 25 applications from the current year yields a sample mean grade point average of 2.90.
Hint: first calculate α/2 using either the lower bound (2.81) or upper bound (2.99); then calculate α. Finally, calculate the probability content of the interval, which is (1- α). And make sure you use the standard error, not the standard deviation, to calculate α/2.
I can't describe steps in Excel since we have to calculate this in a single cell. There is no in built formula to calculate Confidence Interval in Excel. You can input the values in different cells and then using the formula in an other cell you can get the required Confidence Interval. The process of calculating Confidence Interval has shown below.
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