Discussion:
Confidence interval for the population mean: Use of the standard normal
Scenario: The mean diastolic blood pressure for a random sample of 90 people was 92 millimeters of mercury. If the standard deviation of individual blood pressure readings is known to be 12 millimeters of mercury, find a 90% confidence interval for the true mean diastolic blood pressure of all people. Then complete the questions below:
Carry your intermediate computations to at least three decimal places.
a) What is the lower limit of 90% confidence interval?
b) What is the upper limit of 90% confidence interval?