Part (a) Total # of cars turning left = L(t) dt 18 = 1,658 cars
Part (b) NOTE: I originally got an answer of 199.417 cars/hour by rounding to 3 decimal places mid-way through the problem. Would this be acceptable to the AP graders? NO. To be safe, wait until the end to round anything off. L(t) > 150 on the interval (12.428, 16.122). The average value of L over this interval is… L(t) dt 12.428 16.122 1 16.122-12.428 199.426 cars/hour =
Part (c) 200,000 500 = 400 This means that the signal will be required if, during any 2-hour time interval, L(t) dt 400. The graphing calculator shows us that L(t) has a maximum value at t = 14.294 hours. Since this is greater than 400, the intersection WILL be eligible for a traffic signal. Centering around this max gives us a 2-hour interval from 13.294 to 15.294 hours. L(t) dt = 435.8436 13.294 15.294