In a medical experiment, the body weight of a baby rat in the control group after $t$ days was $f(t)=4.96+.48 t+.17 t^{2}-.0048 t^{3}$ grams. (Source: Growth, Development and Aging.)
(a) Graph $f(t)$ in the window $[0,20]$ by $[-12,50] .$
(b) Approximately how much did the rat weigh after 7 days?
(c) Approximately when did the rat's weight reach 27 grams?
(d) Approximately how fast was the rat gaining weight after 4 days?
(e) Approximately when was the rat gaining weight at the rate of 2 grams per day?
(f) Approximately when was the rat gaining weight at the fastest rate?