Question

The effectiveness of a blood-pressure drug is being investigated. An experimenter finds that, on average, the reduction in systolic blood pressure is 30.4 mmHg (millimeters of mercury) for a sample of size 686 and a sample standard deviation 5.5 mmHg. How much of mmHg will lower for a typical patient's systolic blood pressure after taking the drug? Estimate with a 90% confidence.

What is the 90% confidence interval to estimate the population mean? Round your answer to one decimal place.

Answer 1

{30.1,30.7}

Explanation:

`\displaystyle CI=\bar{x}\pm z(s)/(√(n))\\\\CI_(90\%)=30.4\pm1.645\biggr((5.5)/(√(686))\biggr)\\\\CI_(90\%)\approx30.4\pm 0.3\\\\CI_(90\%)=\{30.1,30.7\}`

Thus, we are 90% confident that the true amount of mmHg that is lowered will be between 30.1 and 30.7 mmHg.