The heart rate variability (HRV) of police officers was the subject of research published in a biology journal. HRV is defined as the variation in the time intervals between heartbeats. A measure of HRV was obtained for each in a sample of 308police officers from the same city. (The lower the measure of HRV, the more susceptible the officer is to cardiovascular disease.) For the 79 officers diagnosed with hypertension, a 95% confidence interval for the mean HRV was (9.4,129.1).

For the 229 officers that are not hypertensive, a 95% confidence interval for the mean HRV was (145.7,188.6).

Use this information to complete parts a through d below.

a. What confidence coefficient was used to generate the confidence intervals?

b. Give a practical interpretation of both of the 95% confidence intervals. Use the phrase "95% confident" in your answer.

The researchers can be 95% confident that the true mean HRV for all hypertensive police officers in the city is between __ and __. A similar statement can be made about the police officers without hypertension.(Type integers or decimals. Do not round.)