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Shaft graves in ancient Greece. Refer to the American Journal of Archaeology (Jan. 2014) study of shaft graves in ancient Greece, Exercise 7.46 (p. 335). Recall that you estimated 1.1,, the average number of shafts buried in an cient Greece graves, using data collected for 13 recently discovered grave sites and a 90% confidence interval. However, you would like to reduce the width of the inter- val for pr. a. Will increasing the confidence level to .95 reduce the width of the interval? b. Will increasing the sample size reduce the width of the interval? c. Determine the sample size required to estimate a to within .5 shaft with 90% confidence