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Thread: Rational Functions problem: driver averaged 60mph on 300-mi trip....

  1. #1

    Rational Functions problem: driver averaged 60mph on 300-mi trip....

    Hi there!

    There was a question on my homework worksheet that has me a little confused. I just don't know where to start. It goes like this :

    "A driver averaged 60 miles per hour on a road trip from Santa Cruz to Los Angeles which is nearly 300 miles away. The average speed for going was x and the average speed for returning was y. (Hint : a 600 mile trip averaging 60 miles per hour means 10 total hours). Using Distance/Rate = Time formula, show that :
    y = (30x) / (x-30)"

    It says in the problem that I have to use the Distance/Rate=Time formula, but I am not sure how with this context. Do I have to start out with values and simplify it down to the one in the problem? If anyone can help, it would be greatly appreciated.

  2. #2
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    Quote Originally Posted by kikithecat View Post
    Hi there!

    There was a question on my homework worksheet that has me a little confused. I just don't know where to start. It goes like this :

    "A driver averaged 60 miles per hour on a road trip from Santa Cruz to Los Angeles which is nearly 300 miles away. The average speed for going was x and the average speed for returning was y. (Hint : a 600 mile trip averaging 60 miles per hour means 10 total hours). Using Distance/Rate = Time formula, show that :
    y = (30x) / (x-30)"

    It says in the problem that I have to use the Distance/Rate=Time formula, but I am not sure how with this context. Do I have to start out with values and simplify it down to the one in the problem? If anyone can help, it would be greatly appreciated.
    time required to go was = 300/x .... (Distance/Rate = Time formula)

    time required for return was = 300/y .... (Distance/Rate = Time formula)

    300/x + 300/y = 10

    continue.....
    “... mathematics is only the art of saying the same thing in different words” - B. Russell

  3. #3
    Quote Originally Posted by Subhotosh Khan View Post
    time required to go was = 300/x .... (Distance/Rate = Time formula)

    time required for return was = 300/y .... (Distance/Rate = Time formula)

    300/x + 300/y = 10

    continue.....
    Oh! I see. Now, would you use that equation to isolate y to get the formula from the problem? Thanks so much!

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