A racehorse is running a 10-furlong race. (1 furlong = 220 yards)

As the horse passes each furlong marker (F), its time is recorded.

F| 0 1 2 3 4 5 6 7 8 9 10

T| 0 20 33 46 59 73 86 100 112 124 135

a) What is the approx speed of the horse as it passes the 3rd marker?

(Do I need to come up with an equation?...and find the derivative, to get the speed at that point?)