A bank manager wants to know the mean amount of mortgage paid per month by homeowners in an area. A random sample of 112 homeowners selected from this area showed that they pay an average of $1579 per month for their mortgages. The population standard deviation of such mortgages is $211. a. Find a 97% confidence interval for the mean amount of mortgage paid per month by all homeowners in this area. Round your answers to two decimal places. to dollars e Textbook and Media b. Suppose the confidence interval obtained in part a is too wide. Select all of the ways the width of this interval can be reduced. O Lowering the sample size O Increasing the confidence level O Increasing the sample size O Lowering the confidence levelView PollCles Current Attempt in Progress A department store manager wants to estimate the mean amount spent by all customers at this store at a 98% confidence level. The manager knows that the standard deviation of amounts spent by all customers at this store is $54. What minimum sample size should he choose so that the estimate is within $4 of the population mean? n = i eTextbook and Media Save for Later Attempts: 0 of 5 used Submit AnswerQuestion / 01 14 View Policies Current Attempt in Progress A sample of 18 observations taken from a normally distributed population produced the following data: 28.4 27.5 25.2 25.2 31.3 23.2 26.2 24.3 28.5 37.5 23.6 28.9 27.5 25.1 27.2 25.1 22.5 22.8 Round your answers to three decimal places. a. What is the point estimate of /? X = b. Make a 98% confidence interval for /. c. What is the margin of error of estimate for / in part b? E =