How long does it take an ambulance to respond to a request for emergency medical aid? One of the goals of one study was to estimate the response time of ambulances using warning lights (Ho \& Lindquist, 2001). They timed a total of 67 runs in a small rural county in Minnesota. They calculated the mean response time to be 8.51 minutes, with a standard deviation of 6.64 minutes. Calculate a \(95 \%\) confidence interval for the mean for this set of data.

a. State the desired level of confidence.

b. Calculate the confidence interval and confidence limits. 

1. Calculate the standard error of the mean \(\left(s \mathrm{X}^{-}\right)\). 

2. Calculate the degrees of freedom \((d f)\) and identify the critical value of \(t\). 

3. Calculate the confidence interval and confidence limits.

c. Draw a conclusion about the confidence interval.