#### Answer

The height of water in the bathtub was initially 0 inches. The height increases linearly to about 15 inches in 5 minutes. It then increases more steeply (possibly because the rate at which the water was being filled increased or the bathtub gets smaller beyond 15 inches) for about half a minute to reach a maximum height of about 20 inches.
At about 5 and a half minutes, the height of the water in the bath tub remains constant at 20 inches (possibly because the water was stopped being filled or this is the maximum height of the bathtub) until the 12 and a half minute mark.
There is a minuscule dip in the height of the water in the bath tub at the 12 and a half minute mark (possible because some water was spilt at this point), after which the water height increases back to the 20 inch and remains constant at that level until about 17 and a half minutes.
After ~17.5 minutes, the height of the water in the bath tub decreases at about the same rate at which it initially increased. It decreases to a height of 0 inches at about the 22 minute mark.

#### Work Step by Step

See the answer above