Question

The effectiveness of a blood-pressure drug is being investigated. An experimenter finds that, on average, the reduction in systolic blood pressure is 32.6 for a sample of size 20 and a standard deviation of 8.8. Estimate how much the drug will lower a typical patient's systolic blood pressure (using a 98% 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,

sample size = n = 20

Degrees of freedom = df = n - 1 = 20 - 1 = 19

t_{$\alpha$ /2,df} = 2.539

Margin of error = E = t_{$\alpha$/2,df} * (s /$\sqrt$n)

= 2.539 * (8.8 / $\sqrt$ 20)

= 4.996

The 98% confidence interval estimate of the population mean is,

$\bar x$ - E < $\mu$ < $\bar x$ + E

32.6 + 4.996 < $\mu$ < 32.6 + 4.996

27.604 < $\mu$ < 37.596