1. Determine the t-value in each of the cases.

(a) Find the t-value such that the area in the right tail is 0.01 with 23 degrees of freedom._______(Round to three decimal places as needed.)

(b) Find the t-value such that the area in the right tail is 0.005 with 23 degrees of freedom.______ (Round to three decimal places as needed.)

(c) Find the t-value such that the area left of the t-value is 0.20 with 28degrees of freedom. [Hint: Use symmetry.]______(Round to three decimal places)

(d) Find the critical t-value that corresponds to 95% confidence. Assume 19 degrees of freedom._______(Round to three decimal places as needed.)

2.Conduct the following test at the =0.01 level of significance. Assume that the samples were obtained independently using simple random sampling.Test whether p1p2. Sample data are x1=30, n1=254, x2=38, and n2=302.

The test statistic z0 is_______ (Round to two decimal places as needed.)

The P-value is______(Round to three decimal places as needed.)

Test the null hypothesis. Choose the correct conclusion below.

A.Reject the null hypothesis because there is not sufficient evidence to conclude that p1

B.Do not reject the null hypothesis because there is not sufficient evidence to conclude that p1p2.

C.Reject the null hypothesis because there is sufficient evidence to conclude that p1p2.

D.Do not reject the null hypothesis because there is sufficient evidence to conclude that p1>p2.

3. A doctor wants to estimate the mean HDL cholesterol of all 20- to 29-year-old females. How many subjects are needed to estimate the mean HDL cholesterol within 4 points with 99% confidence assuming s=12.8 based on earlier studies? Suppose the doctor would be content with 90% confidence. How does the decrease in confidence affect the sample size required?

Partial critical value table Level of Confidence, Critical Value, Zo/2 (1 - () . 100% Area in Each Tail, 2 90% 0.05 1.645 95% 0.025 1.96 99% 0.005 2.575 Print Done