A graphing calculator is recommended. If a rock is thrown upward on the planet Mars with a velocity 8 m/s, its height in meters t seconds later is given by y = 8t - 1.86t2. (Round your answers to two decimal places (a) Find the average velocity (in m/s) over the given time intervals. (1) [1, 2] m/s (11) [1, 1.5] m/s (III) [1, 1.1] m/s (iv) [1, 1.01] m/s (v) [1, 1.001] m/s (b) Use your answers from part (a) to estimate the instantaneous velocity of the rock (in m/s) when t = 1. m/s