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It has been found that candidates for an MBA program have undergraduate grade point averages that are normally distributed with standard deviation .45. A random sample of 25 applicants is taken, yielding a sample mean GPA of 2.90. (a) Find a 95% confidence interval for the population mean GPA. (b) Without doing the calculations, state whether a 90% confidence interval for the population mean would be wider or narrower than that in part (a). (c) If we decide to calculate a 95% confidence interval based on a random sample of 20 applicants, would that interval be wider or narrower than the one found in part (a)? (d) In fact, the population standard deviation is . 15. State whether a correctly calculated 95% confidence interval would be wider or narrower than that in part (a)