An individual's income varies with age. The table shows the median income I of individuals of different age groups within the United States for a certain year. For each age group, let the class. midpoint represent the independent variable x. For the class "65 years and older," assume that the class midpoint is 69.5. Complete parts (a) through (e) Age Class Median Midpoint, x Income, I 15-24 years 19.5 $12,965 25-34 years 29.5 $31,130 35-44 years 39.5 $42,637 45-54 years 49.5 $45,693 55-64 years 59.5 $42,478 65 years and older 69.5 $22,500 (b) Use a graphing utility to find the quadratic function of best fit that models the relation between age and median income. The quadratic function of best fit is y=-44.572 x2 + 4209.119 x- 53141.512