# Computing Confidence

In the following exercises, you will compute confidence intervals using Excel. You will submit a single Excel file that includes your results for all of the exercises. For each exercise, please include the output from Toolpak (or whatever tool you are using), and make sure that you clearly show the following:

Confidence level
Whether you should use a normal distribution or t-distribution
Confidence interval in interval form, i.e., (lower bound, upper bound)
Confidence interval in margin of error form, i.e., sample mean ± margin of error.

Exercise#1: A health care professional wants to determine the systolic blood pressure of individuals with hypertension who take Atenolol. Thirty such individuals have an average systolic blood pressure of 105, with a sample standard deviation of 23. Find the 95% confidence interval for mean systolic blood pressure for hypertensive individuals who take Atenolol.

Exercise#2: In a study of the effectiveness of a certain anxiolytic on individuals experiencing panic attacks, out of a 120-person sample, 85 reported a decrease in panic attack frequency. Find the 95% confidence interval for the proportion of patients who experienced a reduction in panic attacks while on the anxiolytic.

Exercise#3: The following is a list of hospital stay durations, in days, of 16 new mothers after cesarean deliveries:

3, 4, 7, 3, 2, 3, 2, 1, 5, 4, 4, 8, 1, 3, 4, 6

Using this sample data, find the 98% confidence interval for the mean duration of post-cesarean hospital stay.

Exercise#4: A camp director is interested in the mean number of letters each child sends during his or her camp session. The population standard deviation is known to be 2.5. A survey of 20 campers is taken. The mean from the sample is 7.9. Find the 99% confidence interval for the mean number of letters.

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