Weights of women of a certain age group are normally distributed with a standard deviation of 17.7 pounds. A researcher wishes to estimate the mean weight of all women in this age groups. Find how large a sample must be drawn in order to be 90% confident that the sample mean will not differ from the population mean by more than 3.5 pounds. As a suggestion, use z to 3 decimal places. 70 69 91 55
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5 pounds, we need to find the z-value corresponding to a 90% confidence level. From the standard normal distribution table, we find that the z-value for a 90% confidence level is approximately 1.645. Show more…
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