Question

On a round trip over the same roads, Sophia averaged 24 mi/h going and 30 mi/h coming back. If the whole trip took 13 1/2 hours, what is the distance one way?

Answer 1

Answer:

d=rt In this problem we are looking for the distance, but we will have to go about it indirectly. If she's traveling the same exact road going and returning, then the distance traveled both ways is exactly the same. Since d = rt, and d is the same, by the substitution property, if and , then , and . So we need to rt for the trip going, rt for the trip returning and set them equal to each other and solve for t. Going is a rate of 24, and the time is t (since we don't know t), and returning is a rate of 30, and the time is 13 1/3-t. (If the whole trip takes 13 1/3 hours, and t is the time going, then the time returning is the difference between the total time and the going time. That concept is one that baffles most algebra students!). So our r1t1 is 24t, and our r2t2 is 30(13 1/3 - t). Set them equal to each other and that will look like this: That fraction of 40/3 is 13 1/3 made into an improper fraction. Distributing that we will have and 54t = 400. That means that t = 7.407. We have time, and that's great, but we need distance! Go back to one of your equations for distance and sub in t and solve for d. d = 24t, and d = 24(7.407), so d = 177.768 miles.