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Chapter 8: Q. 29 (page 393)

Problems 29-38each include a normal probability plot and either a frequency histogram or a stem-and-leaf diagram for a set of sample data. The intent is to use the sample data to perform a hypothesis test for the mean of the population from which the data were obtained. In each case, consult the graphs provided to decide whether to use the z-test, the t-test, or neither: Explain your answer.

29. The normal probability plot and histogram of the data are depicted in Fig. 9.23; σis known.

Short Answer

Expert verified

The sample size is large and σis known.

Step by step solution

01

Step 1. Given Information 

A graph with plotting:

02

Step 2. Observing the graph

Here the sample size is large and also σis known. So, using the z-test appears to be reasonable. But normal probability plot indicates that there may be outliers in the data. So it is necessary to check whether they are potential outliers; if they are, then to check whether the outliers are removable or not. If the potential outliers are not removable, one may use any nonparametric method instead of z-test as the variable under consideration is roughly symmetric.

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Most popular questions from this chapter

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