Last week we went on a trip to the Waitangi River to measure the velocity.

Here is my graph on it

This graph shows that the velocity is  20.21 seconds. 

Let me show you my thinking:

16+18+21+18+17=90

.63+.10+.03+.60+85=2.21

90+2.21=92.21

92.21፥5=18 r2.21

18+2.21=20.21

That is why the velocity of the Waitangi river is 20.21 seconds.