Question

You have data from a sample of 65 workers at a local factory who are full time employees. The mean systolic blood pressure of this sample 120. You know that the population standard deviation (?) of all workers' systolic blood pressure at the local factory is 18."

Which of the below represents the best interpretation of the 95% confidence interval you calculated on the previous question for the unknown population mean systolic blood pressure of local factory workers who are full time employees?

*note: the actual values for the confidence interval limits are left blank intentionally

About 95% of local factory workers who are full time employees have a systolic blood pressure between ___ and ___.

We are 95% confident that the unknown population mean systolic blood pressure of local factory workers who are full time employees falls between ___ and ___.

It is guaranteed that the unknown population mean systolic blood pressure of local factory workers who are full time employees falls between ___ and ___.

We are 95% confident that the sample mean systolic blood pressure of local factory workers who are full time employees falls between ___ and ___.

Answer 1

we have x(bar) or sample mean = 120, sample size (n) = 65 andpopulation standard deviation()=18

we know that using the normal distribution, the z score for 95% confidence interval is 1.96

using the formula for the confidence interval

CI =

setting the given values, we get

CI =

this gives

CI = (115.62,124.38)

Since we are calculating the confidence interval for the unknown population mean, so only option B is matching with the unknown population mean

thus, the final answer is option B

We are 95% confident that the unknown population mean systolic blood pressure of local factory workers who are full time employees falls between 115.62 and 124.38