Water leaks from a tank at the rate of r(t) gallons per hour. the rate decreased as time passed, and values of the rate at two-hour time intervals are shown in the table below. the total amount of water that leaked out is evaluated by a riemann sum. find the upper estimate (left end-points of each rectangle) for the total amount of water that leaked out by using five rectangles.

give your answer with one decimal place.

t (hr) 0 2 4 6 8 10
r(t) (gal/hr) 8.7 7.6 6.8 6.2 5.7 5.3

i believe it's 70.0 because 10-0/5=2 and 2*(8.7+7.6+6.8+6.2+5.7). is this correct or is it 8-0/5 and then the rest?