The annual income of residents in a county is $42,000 with a standard deviation of $10,000. between what two values do 95% of the incomes of county residents lie?

We are assuming in this problem that the data points are uniformly distributed so as to use the z-score to determine what is asked in the problem. In this case, we are given with 4200$ mean and 10000$ standard deviation. according to bell curve distribution, 95% of the data points lie within +- 2 SD which means the points are 42000 +- 10000 that is (32,000$, 52,000$)