Suppose there were reason to believe that incomes in some population were normally distributed, with a mean of $47,000 per year, and a standard deviation of $5,500 per year.
a. What fraction of the population would make between $40,000 and $55,000 per year?
b. What fraction of the population would be described as below the poverty level, if that number is $22,350 (assuming a single wage-earner supporting a family of 4)?
c. If used blindly, this distribution would suggest that some people earn negative income per year. What fraction would that be?
d. We hear a lot these days about 1% / 99%. In this distribution, what is the minimum income of someone in the top 1%?