A 2-L plastic pop bottle is filled with water. A hole is made in the base of the bottle. As the water drains out, the height of the water level in the bottle drops. The table show the height of there at 20 s intervals.

Time t (s)	Height h (mm)
0	130
20	105
40	83
60	64
80	48
100	34
120	22
140	13
160	6
180	2
200	0

a) Calculate the average rate of change between 0 s and 100 s and 100 s to 200 s.

b) Does the bottle drain at a constant rate? Explain your reasoning.

c) What does the negative rates of change indicate?

d) Make as good an estimate as possible of the instantaneous rate of change of water height at t = 60 s.