9.87 For the following simple random sample of household incomes (thousands of dollars) from a large county, construct and interpret the 90% and 95% confidence intervals for the population mean. The data are also in file XR09087.

58.3 50.0 58.1 33.5 51.1 38.1 42.3 60.4 55.8 46.2 40.4 52.5 51.3 47.5 48.5 59.3 40.9 37.1 39.1 43.6 55.3 42.3 48.2 42.8 61.1 34.7 35.5 52.9 44.7 51.5