The effectiveness of a blood-pressure drug is being investigated.

Question

The effectiveness of a blood-pressure drug is being investigated. An experimenter finds that, on average, the reduction in systolic blood pressure is 31.2 for a sample of size 491 and standard deviation 20.4.

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).

Answer 1

31.2 +/-(1.96)20.4/sqr491, n=491, s=20.4, xbar=31.2 alpha=1-.95 =.05, z=1.96

= 31.2 +/- 39.2/22.16

=31.2 +/-1.77

= (30.2, 33.0) rounded to one decimal

or

30.2 < x < 33.0