# Total cholesterol in children aged 10-15 is assumed to follow a

Statistical Computing Using Excel. Please save your results as a 97/2003 Excel file. Answers should be in the same workbook and 5.1 practice problems on Worksheet 1, 6.6 problems on Worksheet 2 and 7.9 Practice Problems on worksheet 3. Highlight the answers.

5.1 Practice Problems (Worksheet 1)

1. Total cholesterol in children aged 10-15 is assumed to follow a normal distribution with a mean of 191 and a standard deviation of 22.4.

a. What proportion of children 10-15 years of age have total cholesterol between 180 and 190?

b. What proportion of children 10-15 years of age would be classified as hyperlipidemic (Assume that hyperlipidemia is defined as a total cholesterol level over 200)?

c. What is the 90th percentile of cholesterol?

2. Among coffee drinkers, men drink a mean of 3.2 cups per day with a standard deviation of 0.8 cups. Assume the number of coffee drinks per day follows a normal distribution.

a. What proportion drink 2 cups per day or more?

b. What proportion drink no more than 4 cups per day?

c. If the top 5% of coffee drinkers are considered heavy coffee drinkers, what is the minimum number of cups consumed by a heavy coffee drinker? Hint: Find the 95th percentile.

6.6 Practice Problems (Worksheet 2)

3. A study is run to estimate the mean total cholesterol level in children 2-6 years of age. A sample of 9 participants is selected and their total cholesterol levels are measured as follows.

185 225 240 196 175 180 194 147 223

Generate a 95% confidence interval for the true mean total cholesterol levels in adults with a history of hypertension.

7.9 Practice Problems (Worksheet 3)

1. The following data were collected in a clinical trial evaluating a new compound designed to improve wound healing in trauma patients. The new compound was compared against a placebo. After treatment for 5 days with the new compound or placebo the extent of wound healing was measured and the data are shown below.

Percent Wound Healing

Treatment 0-25% 26-50% 51-75% 76-100%

New Compound (n=125) 15 37 32 41

Placebo (n=125) 36 45 34 10

Is there a difference in the extent of wound healing by treatment? (Hint: Are treatment and the percent wound healing independent?) Run the appropriate test at a 5% level of significance.

2. Use the data in Problem #1 and pool the data across the treatments into one sample of size n=250. Use the pooled data to test whether the distribution of the percent wound healing is approximately normal. Specifically, use the following distribution: 30%, 40%, 20% and 10% and a=0.05 to run the appropriate test.

3. The following data were collected in an experiment designed to investigate the impact of different positions of the mother on fetal heart rate. Fetal heartrate is measured by ultrasound in beats per minute. The study included 20 women who were assigned to one position and had the fetal heart rate measured in that position. Each woman was between 28-32 weeks gestation. The data are shown below.

Back Side Sitting Standing

20 21 24 26

24 23 25 25

26 25 27 28

21 24 28 29

19 16 24 25

Is there a significant difference in mean fetal heart rates by position? Run the test

at a 5% level of significance.