Rtgrove123

This is the question:

Sharon is on a train that is traveling at a constant speed. Consecutively numbered markers are located along the track at 66 meter intervals. Exactly 3 minutes after she passes marker number 1, she passes marker number n+1. In terms on n, what is the speed of the train, in meters per minute?

A. 198/n
B. 198/(n+1)
C. 22n
D. 22(n+1)
E. 66(n+1)

Correct Answer: C

Ok, well this is what I did. I first found the distance the train travels in terms of n: 66n. Then I found the time in minutes that the train would travel, which is 3n. Then you get 66n/3n or just 22.

I don't understand, however, how 22n is the answer. The question says that the train travels at a constant speed; conversely, with a speed of 22n, the speed would increase as its distance increases.

If someone could guide me in the right direction I'd really appreciate it!

THANKS,
Robbie

fignewton

You're almost there. The distance is 66n as you obtained, but the train travels that far in 3 minutes, not 3n minutes, so the speed is 66n/3 = 22n.

If n were bigger for another train, then you're right, 22n is bigger and the speed is faster. But that is because the new train is covering a bigger distance (66n) in the same time (3 minutes).