• Figure 5.11 shows the velocity of a car for 0 ≤ t ≤ 12 and the rectangles used to estimate the distance traveled. Velocity versus time graph from 0 to 4 and 0 to 12 respectively shows concave up decreasing curve passing through top left corners of rectangles such as (0, 4), (4, 2), and (8, 1). Figure 5.11 (a) Do the rectangles represent a left or a right sum? (b) Do the rectangles lead to an upper or a lower estimate? (c) What is the value of n? (d) What is the value of Δt? (e) Give an approximate value for the estimate.