The National Assessment of Educational Progress (NAEP) gave a test of basic arithmetic and the ability to apply it in everyday life to a sample of 840 men 21 to 25 years of age. Scores range from 0 to 500; for example, someone with a score of 325 can determine the price of a meal from a menu. The mean score for these 840 young men was

x= 272. We want to estimate the mean score in the population of all young men. Consider the NAEP sample as an SRS from a Normal population with standard deviation

= 60.

a)According to the 95 part of the 68-95-99.7 rule, 95% of all values ofxfall within _______ on either side of the unknown mean. What is the missing number?

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b)What is the 95% confidence interval for the population mean scorebased on this one sample? Note: Use the 68-95-99.7 rule to find the interval.

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