BR Physics Ch.1 Practice Exam Passage 7 ? 48!! Help

[PhysioG318]

I have read the answer explanation however I still do not understand bow they arrived to the conclusion. If someone who is studying BR physics can assist me I would greatly appreciate it. The answer is 25:31 however I dont understand why choice A.) is not correct being 31:25

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[drspacheman]

You are given the velocities of car A and car C, but asked for the time. The equation for velocity is v=DeltaX/t. From this we can see that velocity is inversely proportional to time. So if we want the ratio of tA:tC (same as tA/tC), then we would want to use the inverse of velocities given, which is vC/vA.

tA/tC = vC/vA = 25/31

 

[PhysioG318]

Thank you that was very helpful!!!!��