Question

The effectiveness of a blood-pressure drug is being investigated. An experimenter finds that, on average, the reduction in systolic blood pressure is 69.6 for a sample of size 22 and standard deviation 6.4. Estimate how much the drug will lower a typical patient's systolic blood pressure (using a 90% confidence level). Assume the data is from a normally distributed population.

Enter your answer as a tri-linear inequality accurate to three decimal places.

___< μ <___

Answer 1

Solution :

Given that,

t _/2,df = 1.721

Margin of error = E = t_/2,df * (s /n)

= 1.721 * (6.4 / 22)

Margin of error = E = 2.348

The 90% confidence interval estimate of the population mean is,

- E < < + E

69.6 - 2.348 < < 69.6 + 2.348

67.252 < < 71.948