1.Suppose you will perform a test to determine whether there is sufficient evidence to support a claim of a linear correlation between two variables. Find the critical values of r given the number of pairs of data n and the significance level .

n = 19, = 0.01

2.Given the linear correlation coefficient r and the sample size n, determine the critical values of r and use your finding to state whether or not the given r represents a significant linear correlation. Use a significance level of 0.05.

r =-0.466, n = 15

3.Provide an appropriate response.

A nutritionist wants to conduct a study to validate the efficacy of an herb as an aid in weight loss. She randomly assigns half of a group of overweight persons to a treatment group who are given the herb with instructions as to use and a planned diet for six weeks. The other half of the group is given the same diet without the herb. Participants are aware as to which group they belong. A nurse at the nutrition center weighs each subject on Friday of each week. Identify any problems that are likely to cause confounding.

A. The study is essentially free of confounding sources.

B. Method of assignment to treatment and control groups

C. The placebo effect

D. Experimenter effect

Find the coefficient of variation for each of the two sets of data, then compare the variation. Round results to one decimal place.

The customer service department of a phone company is experimenting with two different systems. On Monday they try the first system which is based on an automated menu system. On Tuesday they try the second system in which each caller is immediately connected with a live agent. A quality control manager selects a sample of seven calls each day. He records the time for each customer to have his or her question answered. The times (in minutes) are listed below.

Automated Menu: 11.1 | 7.4 |2.9 |9.2 | 6.3 | 5.5

Live Agent: 6.6| 2.7| 4.1 |4.1| 3.4| 5.2| 3.7