Question

An old row boat has sprung a leak. Water is flowing into the boat at rate, r(t), given the table, t (minutes) 0,5,10,15. and r(t) (liters/min) 12, 20, 24,16. compute upper and lower estimates for the volume of water that has flowed into the boat during the first 15 minutes.

Answer 1

you can use rectangles

Answer 2

integral r(t) dt on [0,15] will give you the exact volume that has flowed into the boat during that time.
but we are not given an explicit formula for r(t), we are given points on the graph