A traffic engineering firm contacted you to assist in designing a study of traffic delay at intersections with signal on urban streets. Three types of signals were to be used in the study: TS1- Pretimed; TS2- Semi-actuated; TS3- Fully actuated. The measure of traffic delay used in the study will be the average stopped time per vehicle (seconds/vehicle) on a Tuesday during the period 7 am to 6 pm at each of r randomly selected intersections. What is the minimum number of intersections, r, that would be needed for each of the three signaling devices so that an = .01 test would have a probability of 90% to detect that the true mean traffic delays were 1 = 20, 2 = 18, and 3 = 16 seconds per vehicle? Use ^2 = 12 in your solution.