Car X is 40 miles west of Car Y. Both cars are traveling east, and Car X is going 50% faster than Car Y. If both cars travel at a constant rate and it takes Car X 2 hours and 40 minutes to catch up to Car Y, how fast is Car Y going?
Answer:
Answer given in the book is (though below answer is copied from beatthegmat.com):
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Answer:
[Reveal] Spoiler:
30 miles per hour
Answer given in the book is (though below answer is copied from beatthegmat.com):
[Reveal] Spoiler:
Let speed of Y = V ,
speed of X = 1.5 V,
relative speed of X wrt Y (catch up speed of X) = 0.5V.
Now catch up speed = (distance between X and Y)/time.
0.5 V = 40 miles / (8/3 hour),
so V = 30 miles/hr.
However, what I don't understand is that the distance traveled by Car Y while Car X is catching up is not factored into the problem. Could someone clarify if my concern is valid, if not then reason.
Thanks,
Kiran
speed of X = 1.5 V,
relative speed of X wrt Y (catch up speed of X) = 0.5V.
Now catch up speed = (distance between X and Y)/time.
0.5 V = 40 miles / (8/3 hour),
so V = 30 miles/hr.
However, what I don't understand is that the distance traveled by Car Y while Car X is catching up is not factored into the problem. Could someone clarify if my concern is valid, if not then reason.
Thanks,
Kiran