Rosner biostatistics 7th edition obstetrics question 621631

Rosner biostatistics 7th edition, obstetrics question 6,21....6,31: can someone explain how to answer these questions, step by step..? (figure 6.4b page167, the questions about obstetrics are on page 197 in the book) figure 6b plotted the sampling distribution of the mean from 200 samples of size 5 from the population of 1000 birthrights given in table 6.2 The mean of the 1000 birthrights in table 6.2 is 112.0 oz with standard deviation 20.6oz. If the central-limit theorem holds, what proportion of the sample means should fall within 0,5 lb of the population mean (112.0 oz)? And within 1 lb?

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