The median weight of a boy whose age is between 0 and 36 months can be approximated by the function w(t) = 7.18+1.41t - 0.000912 +0.000133t, where t is measured in months and w is measured in pounds. Use this approximation to find the following for a boy with median weight in parts a) through c) below. a) The rate of change of weight with respect to time. w'(t) = 0