# Question

Why do you need to know the sampling distribution of the difference between two sample means in order to perform a hypothesis test to compare two population means?

## Answer to relevant Questions

Refer to Exercise 10.44 and find a 98% confidence interval for the difference between the mean IQs of school-age children without and with the dexamethasone therapy. The formula for the pooled variance, s2p, is given on page 397. Show that, if the sample sizes, n1 and n2, are equal, then s2p is the mean of s21 and s22. Suppose that you want to perform a hypothesis test to compare the means of two populations, using independent simple random samples. Assume that the two distributions of the variable under consideration have the same shape, ...x1 = 20, s1 = 2, n1 = 30, x2 = 18, s2 = 5, n2 = 40 a. Right-tailed test, α = 0.05 b. 90% confidence interval We have provided summary statistics for independent simple random samples from two populations. In each case, use ...Refer to Exercise 10.73 and find a 90% confidence interval for the difference between the mean numbers of acute postoperative days in the hospital with the dynamic and static systems.Post your question

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