If a rock is thrown upward on the planet Mars with a velocity of 10 mys, its height in meters t seconds later is given by y=10t-1.86t^2. (a) Find the average velocity 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) Estimate the instantaneous velocity when t=1.