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Construct a 90% confidence interval for the population mean.

Construct a 90% confidence interval for the population mean. Assume the population has a normal distribution. A sample of 15 randomly selected students has a grade point average of 2.86 with a standard deviation of 0.78.
a. (2.37, 3.56)
b. (2.51, 3.21)
c. (2.41, 3.42)
d. (2.28, 3.66)

Solution Preview

Mean = 2.86

Z for 90% = 1.65(from Normal Tables)

Upper CI ...

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