8) A runner was training for a 21 mile long race. The distance D (in miles) in function of time t (in weeks) is given by: D = 2(t-1)² +15 a) b) c) How many miles have done the runner in the first week? What is the average rate of training between the first and the third week? dD Calculate the derivative of D with respect to time dt and explain the obtained answer.

(b) Find the derivative, d af si dar sin (vt) dt.

The deck of a bridge is suspended 285 feet above a river. If a pebble falls off the side of the bridge, the height, in feet, of the pebble above the water surface after t seconds is given by  y = 285 − 16t2. (a) Find the average velocity (in ft/s) of the pebble for the time period beginning when t = 2 and lasting the following amount of time. (i) 0.1 seconds  (ii)0.05 seconds  (iii)0.01 seconds  (b) Estimate the instantaneous velocity (in ft/s) of the pebble after 2 seconds.

Please show a check :)