4. Identify the vertex, focus, and directrix. y=1/12x^2

O vertex (0, 0); focus (3, 0); directrix at y = 3
O vertex (0, 0); focus (3, 0); directrix åt y = -3
O vertex (0, 0); focus (0, 3); directrix at y = 3
O vertex (0, 0); focus (0, 3); directrix at y = -3

Data from 2005 for various age groups show that for each $100 increase in the median weekly income for whites, the median weekly income of blacks increases by $105. also, for workers of ages 25 to 54 the median weekly income for whites was $676 and for blacks was $527. (a) let w represent the median weekly income for whites and b the median weekly income for blacks, and write the equation of the line that gives b as a linear function of w. b = (b) when the median weekly income for whites is $760, what does the equation in (a) predict for the median weekly income for blacks?