Question

Use the given degree of confidence and sample data to construct a confidence interval for the population proportion p.

Of 117 randomly selected adults, 35 were found to have high blood pressure. Construct a 95% confidence interval for the true percentage of all adults that have high blood pressure.

Answer 1

Here we want to construct a 95% confidence interval for the true percentage of all adults that have high blood pressure.

Let' write given information.

n = sample size = 117

x = number of adults who have high blood pressure = 35

Confidence level = c = 95%

Let's used minitab to construct confidence interval for population proportion ( P )

Step 1) Click on Stat>>>Basic statistics>>>1-proportion...

Step 2) select summarized data

number of events = x = 35

Number of trials = n = 117

Step 3) click on option

The given confidence level is = 95.0

so put "Confidence level " = 95.0

Alternative = not equal

then click on "Use test and interval based on normal approximation"

Then click on OK and again click on OK

So we get the following output

From the above output the 95% confidence interval for population proportion is (0.216177, 0.382113)