On a coordinate plane, a parabola opens up. It goes through (negative 3.25, 5), has a vertex of (1.7, negative 2.75), and goes through (6.25, 5). Solid circles appear on the parabola at (negative 3, 4), (0, negative 2), (1.5, negative 2.75), (3, negative 2), (6, 4). Which is the rate of change for the interval between 3 and 6 on the x-axis?