a. According to the curve, the bottom 80% of families has about 58% of the income, so the top 20% has about 42%.
b. The bottom 60% of families have about 32% of the income, and the bottom 40% of families have about 16% of the income. So the third quintile has about 32% − 16% = 16%.
Given that the budget is $24 and the minimum is 7 tubs, the fourth graph shows the area in which both constraints are satisfied: triangular area between the points
