The body mass of yearling bighorn sheep on Ram Mountain in Alberta, Canada, can be estimated by
M(t) = 27.5 + 0.3t - 0.001t²
where M1t2 is measured in kilograms and t is days since May 25.

(a) Find the average rate of change of the weight of a bighorn yearling between 105 and 115 days past May 25.
(b) Find the instantaneous rate of change of weight for a bighorn yearling sheep whose age is 105 days past May 25.
(c) Graph the function M(t) on [5, 125] by [25, 65].