7) The high price of medicines is a source of major expense for those seniors in the United States who have to pay for these medicines themselves

7) The high price of medicines is a source of major expense for those seniors in the United States who have to pay for these medicines themselves. A random sample of 2000 seniors who pay for their medicines showed that they spent an average of $ 4600 last year on medicines with a standard deviation of $ 800. a- Make a 98% confidence interval for the corresponding population mean. b- Suppose the confidence interval obtained in part a is too wide. How can the width of this interval be reduced? Discuss allpossible alternatives. Which alternative is the best?