A child inflates a balloon, admires it for a while and then lets the air out at a constant rate. If V (t) gives the volume of the balloon at time t, then Figure 2.32 shows V'(t) as a function of t. At what time does the child:
(a) Begin to inflate the balloon?
(b) Finish inflating the balloon?
(c) Begin to let the air out?
(d) What would the graph of V'(t) look like if the child had alternated between pinching and releasing the open end of the balloon, instead of letting the air out at a constant rate?

-2 3 6 v't) 9 + 12 Figure 2.32 15 18