Question

The effectiveness of a blood-pressure drug is being investigated. An experimenter finds that, on average, the reduction in systolic blood pressure is 25.3 for a sample of size 322 and standard deviation 20.1.

Estimate how much the drug will lower a typical patient's systolic blood pressure (using a 95% confidence level).

Enter your answer as a tri-linear inequality accurate to one decimal place (because the sample statistics are reported accurate to one decimal place).

__ < μμ < __

Answer should be obtained without any preliminary rounding.

Answer 1

Solution :

Given that,

Z/2 = Z_0.025 = 1.96

Margin of error = E = Z/2 * ( /n)

= 1.96 * ( 20.1 /  322 )

= 2.2

At 95% confidence interval estimate of the population mean is,

- E < < + E

25.3 - 2.2 <   < 25.3 + 2.2

( 23.1 <   < 27.5 )