PSAT Math question

<p>This is the question:</p>

<p>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?</p>

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

<p>Correct Answer: C</p>

<p>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. </p>

<p>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.</p>

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

<p>THANKS,
Robbie</p>

<p>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.</p>

<p>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).</p>