# Question

When is it appropriate to use stratified random sampling? What are strata, and how should strata be selected?

## Answer to relevant Questions

Explain how to take a systematic sample of 100 companies from the 1,853 companies that are members of an industry trade association. Explain how each of the following changes as the number of degrees of freedom describing a t curve increases: a. The standard deviation of the t curve. b. The points tα and tα/2. The mean and the standard deviation of the sample of 65 customer satisfaction ratings in Table are 42.95 and 2.6424, respectively. Calculate a t-based 95 percent confidence interval for μ, the mean of all possible customer ...Referring to Exercise 8.12b (page 299), assume that the population standard deviation equals .66. How large a sample of late replacement buyers is needed to make us? In exercise Suppose that a random sample of 500 late ...Suppose that 60 percent of 1,000 randomly selected U.S. adults say that they take part in some form of daily activity to keep physically fit. Based on this finding, find a 95 percent confidence interval for the proportion of ...Post your question

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