Assume you are an observer standing at a point on a three lane race track. All vehicles in lane 1 are traveling at 30 mi/h, all vehicles in lane 2 are traveling at 40 mi/h, and all vehicles in lane 3 are traveling at 50 mi/h. There is a constant spacing of 0.25 mile. If you collect spot speed data for all vehicles that pass your observation point in one hour, what will the time-mean speed be for the traffic stream?