1. To test the efficacy of a new cholesterol-lowering medication, 10 people are selected at random. Each has their LDL levels measured (shown below as Before), then take the medicine for 10 weeks, and then has their LDL levels measured again (After).

Give a 92.4% confidence interval forBA, the difference between LDL levels before and after taking the medication.

Confidence Interval =

2. A matched pairs experiment is carried out, yielding the following data:

nD=60,xD=1.4,sD=7.2

Is there evidence, at an=0.04level of significance, to conclude that there is a difference between the two sets of measurements? Carry out an appropriate hypothesis test, filling in the information requested.

A. The value of the standardized test statistic:

B. The p-value is:

3. Two statistics teachers both believe that each has the smarter class. To put this to the test, they give the same final exam to their students. A summary of the class sizes, class means, and standard deviations is given below:

n1=43,n2=40,x1=83.6,x2=79.5,s1=15.1s2=17.4

n1=43,x1=83.6,s1=15.1n2=40,x2=79.5,s2=17.4

Is there evidence, at an =0.02=0.02 level of significance, to conclude that there is a difference in the two classes? Carry out an appropriate hypothesis test, filling in the information requested.

A. The value of the standardized test statistic:

B. The p-value is

4. "Conservationists have despaired over destruction of tropical rain forest by logging, clearing, and burning." These words begin a report on a statistical study of the effects of logging in Borneo. Here are data on the number of tree species in 12 unlogged forest plots and 9 similar plots logged 8 years earlier:

Unlogged 22 18 22 20 15 21 13 13 19 13 19 15

Logged 17 4 18 14 18 15 15 10 12

Use the data to give a 90% confidence interval for the difference in mean number of species between unlogged and logged plots. Compute degrees of freedom using the conservative method.