Kinematics Question

[Lunasly]

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Hello everyone,

Q: Two cars, a Chevette and an Aries, where travelling at 25 m/s and 31 m/s, respectively. The Chevette will travel 12.5m in time(c) and the Aries will travel 12.5m in time(a). Assuming their velocities are constant, what is the ratio of time(a) to time(c)?

A) 31:25
B) 1:1
C) 25:31
D) 15.5:2

The answer is C.

Now I have boiled the answer down to choices A and C. What I don't get it why it is answer C over answer A. I can think of it logically that the Aries which travels faster will be able to travel 12.5m in less time, thus answer C makes sense. The question I am asking you all is: How do you prove that mathematically?

Thanks,
Lunasly.

 

[milski]

tc=12.5/25
ta=12.5/31

ta:tc= (12.5/31) : (12.5/25) = (1/31) : (1/25) = 25:31

 

[Lunasly]

Ah right. I accidentally had A and C backwards so it turned out to be 31:25 but when you cross multiply its supposed to be 25:31.

Thanks man.