You are riding on a roller coaster whose path can be modeled by y = 0.005x^2 - 2x + 200 where x and y are measured in feet. When t = 0 seconds, you are at the point (0, 200).
(a) When t = 4 seconds, the y-coordinate of your location is 32 feet high. What is the x-coordinate of your location in feet? (t is not part of the equation)
(b) When t = 4.23 seconds, the y coordinate of your location is 18 feet high. what is the x coordinate of your location in feet. (t is not part of the equation).
(c) What was your average speed in feet/sec between the two points? (enter the nmber rounded to the nearest whole number.)
I got part (a) and (b), they are 120 and 140 but I just don't know how to get part (c).