A graphing calculator is recommended. If a rock is thrown upward on the planet Mars with a velocity 7 m/s, its height in meters t seconds later is given by y = 7t - 1.86t2. (a) Find the average velocity (in m/s) over the given time intervals. (i) [1, 2] (ii) [1, 1.5] (iii) [1, 1.1] (iv) [1, 1.01] (v) [1, 1.001] (b) Use your answers from part (a) to estimate the instantaneous velocity of the rock (in m/s) when t = 1