A random sample of the costs of repair jobs at a large muffler repair shop produces a mean of $127.95 and a standard deviation of $24.03. If the size of this sample is 40, which of the following is an approximate 90 percent confidence interval for the average cost of a repair at this repair shop? (A) $127.95±$4.87 (B) $127.95±$6.25 (C) $127.95±$7.45 (D) $127.95±$30.81 (E) $127.95±$39.53

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