Data from a social survey for 2016 show that the average income in a city is 2106. For a sample size of 1806 individuals, 1159 of them have an income below the average. a) Obtain a confidence interval for a confidence level of 98% for the proportion of individuals whose income is above the mean. b) What sample size would be necessary to control a maximum margin of error of 1% at the same level of confidence, suppose that the proportion has not changed.