A coin is dropped from a height of 750 feet. The height, s, (measured in feet), at time, t (measured in seconds), is given by s= -16t2 + 750. a) Find the average velocity on the interval [1, 3]. b) Find the instantaneous velocity when t = 3. c) How long does it take for the coin to hit the ground? d) Find the velocity of the coin when it hits the ground. For (a), I graphed the equation on my calculator and found y = 686 when x = 2 (the average of 1 and 3). I don't know if that's the right thing to do though. For (b), I simply plugged t = 3 into the equation given and got 606. Again, I don't know if that's the right thing to do. For (c), I found when y = 0, x was 6.84. That doesn't seem like a logical time though. I wasn't quite sure how to do (d), and I have the sneaking suspicion I'm not doing any of these right. Any help with any of the sections is appreciated!!