18. Suppose 24 powderpost beetles are left inside a wood barn undisturbed. The beetle population doubles in size every week. The equation P(x) = 24(2*) can be used to determine the number of beetles after x weeks. Calculate the average growth rate for the beetle population for the first five weeks [0, 5]. 19. Suppose the total cost in dollars to produce x widgets is given by the function C(x) = 0.0002x3 + 0.09x2 + 12x + 1500. A. Find the average rate of change of the total cost when the number of widgets produced increases from 100 to 300 items. B. Find the average rate of change of the total cost when the number of widgets produced increases from 200 to 500 items. * 20. Suppose an object is launched upward with an initial velocity of 48 feet per second from a height of 80 feet. The height of the object t seconds after it is launched is given by the function h(t) = -16t2 + 48t +80. A. Find the average velocity in the first two seconds after the object is launched. B. Find the average velocity from t = 2 to t = 4 seconds