Poverty thresholds are determined by the U.S. Census Bureau. A poverty threshold represents the minimum annual household income for a family not to be considered poor. In 2009, the poverty threshold for a family of four with two children under the age of 18 years was $21,756. In 2017, the poverty threshold for a family of four with two children under the age of 18 years was $24,858. Assuming that poverty thresholds increase in a straight-line fashion, use the midpoint formula to estimate the poverty threshold for a family of four with two children under the age of 18 in 2013. How does your result compare to the actual poverty threshold in 2013 of $23,624?