Give a comment on this work.

We are interested in the average wait estimated time of our local ER at 7 PM on Friday nights. So, we sample 18 estimated wait times (in minutes) at 7 PM on Friday nights over the last 2 years and found the following:

3, 8, 25, 47, 61, 25, 10, 32, 31, 20, 10, 15, 7, 62, 48, 51, 17, 30

Using these ER wait times, construct a 90% confidence interval for the mean ER wait times for Friday nights at 7 PM

1. What are the sample mean and sample standard deviation of this data set?

The sample mean and standard deviation for the data set, when rounding to the nearest tenth, are 28 and 19.

2. Should we be using the Z or T distribution? Explain why.

We should be using the critical T-test because we will be estimating the sample standard deviation.

3. Find the Critical Z or T value for this problem.

The critical T value of the given data set is 1.328. The significance level of 0.10 and the degrees of freedom are 19.

4. Compute the Margin of Error, E

The margin of error for the given data set is 4.446

5. Write out the confidence interval

The 90% confidence interval falls between 21 and 28 minutes of wait time.

6. The ER claims its average wait time on Friday nights will be less than 35 minutes. Based on our confidence interval, does this seem like a valid claim?

Based on our confidence interval I would say that this is a valid claim; the average wait time for the ER is less than 35 minutes.