ok so i've been given this problem and i'm not exactly sure what to do:

here is the data for the speed of a sailboat at 15-min intervals (the speed is in knots)

time/speed

1:00/12

1:15/27

1:30/35

1:45/38

2:00/41

2:15/44

2:30/20

i have to estimate the total distance sailed during the 1 and 1/2 hour period.