Question

The effectiveness of a blood-pressure drug is being investigated. An experimenter finds that, on average, the reduction in systolic blood pressure is 16.4 for a sample of size 22 and standard deviation 10.9. 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.

Answer 1

Solution :

Given that,

Point estimate = sample mean = = 16.4

sample standard deviation = s = 10.9

sample size = n = 22

Degrees of freedom = df = n - 1 = 22-1 = 21

t _/2,df = 1.72

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

= 1.72 * ( 10.9/ 22)

Margin of error = E = 3.999

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

- E < < + E

16.4 - 3.999 < < 16.4 + 3.999

12.401 < < 20.399

(12.401,20.399)