Question

The effectiveness of a blood-pressure drug is being investigated. An experimenter finds thaton average, the reduction in systolic blood pressure is 49 for a sample of size 25 and standard deviation 15. Estimate how much the drug will lower a typical patient's systolic blood pressure (using a 80% confidence level) Give your answers to one decimal place and provide the point estimate with its margin of error.

Answer 1

Given:

`\begin{gathered} \bar{x}=49 \\ n=25 \\ s=15 \\ C.I=80\text{ \%} \end{gathered}`

Using the formula;

`C.I=\bar{x}\pm z(s)/(√(n))`

The z-score for 80% confidence interval is given by 1.28

Hence,

`\begin{gathered} =49\pm1.28((15)/(√(25))) \\ =49\pm1.28((15)/(5)) \\ =49\pm1.28(3) \\ =49\pm3.84 \end{gathered}`

Hence, the point estimate with its margin of error to one decimal place is;

`49\pm3.8`