What are the degrees of freedom for an independent-samples t-test using two samples with n = 20 in each sample?

True/false: Some researchers have suggested that blood pressure may tend to be higher on average when measured on a subject's right arm than on their left arm. A doctor decided to investigate this conjecture by taking readings of the systolic blood pressure on both arms of a random selection of twelve patients at his practice. A paired samples t-test can be applied.

You are conducting a study to see if the proportion of voters who prefer Candidate A is significantly more than 0.71. Thus you are performing a right-tailed test. Your sample data produce the test statistic z = 3.006. Find the p-value accurate to 4 decimal places. p-value =

You may need to use the appropriate appendix table or technology to answer this question. The following results are for independent random samples taken from two populations. Sample 1 Sample 2 n1 = 20 n, = 30 X1 = 22.7 X2 = 20.1 s, = 2.3 2 = 4.6 (a) What is the point estimate of the difference between the two population means? (Use x, - x,.) 2.72 (b) What is the degrees of freedom for the t distribution? (Round your answer down to the nearest integer.) 48 (c) At 95% confidence, what is the margin of error? (Round your answer to one decimal place.) 1.9 (d) What is the 95% confidence interval for the difference between the two population means? (Use x, - Round your answers to one decimal place.) .6 to 4.4