Re: Two cars are traveling side-by-side along the same road. At
[#permalink]
10 Dec 2013, 11:57
Two cars are travelling side-by-side along the same road. At time 0, car 1 turns off onto another road. Two hours later, both cars are at the same horizontal position on their respective roads, as illustrated. If both cars were travelling at constant speeds for those entire two hours, how many times faster was car 1 travelling than car 2?
Trying to solve this in two minutes, I misread the question and thought that the time spent traveling included distance before the car 1 and car 2 split up. I said the answer was E because we had no idea how for they drove on the straight line before car 1 departed the straight line. Obviously, this question is considering just how long they were driving starting from the point at which they hit the triangle.
(1) Car 1 travelled 80 miles during those two hours.
If the cars are aligned horizontally at the end of the trip then their coordinates form a triangle. The shallower the angle on the left side of the triangle, the less distance 1 is going to travel in relation to car 2. A steeper angle would mean that car 1 would travel more distance and would have to do it at a quicker speed if they were to converge at the same x-coordinate at the same time. We have no idea how many miles 2 traveled in this time. The angle could have been quite steep: car 2 could have traveled 4 miles and car 1 80 in which case car 1's speed is much greater than car 2's. The angle could have been very shallow and car 2 could have traveled 70 miles and car 1, 80, in which case their speeds would have been much closer. Insufficient.
(2) The two roads form a 60˚ angle.
This tells us exactly what we need to know. Because both cars are aligned on the x-coordinate, they form a right angle. We know that the angle on the left of the triangle is 60 so this is a 30:60:90 triangle, the ratios of such are x: (√3/2 x): 2x meaning the ratio of the distance traveled by car 1 to car 2 is 2:1. Sufficient.
B.