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LiquidFireAK
- Junior | Next Rank: 30 Posts
- Posts: 16
- Joined: Tue Oct 29, 2013 6:47 am
For the question below, I assume the formula is Distance = Rate X Time, however the solution doesn't seem to be using it... can any experts explain why:
After driving to a riverfront parking lot, Bob plans to
run south along the river, turn around, and return to
the parking lot, running north along the same path.
After running 3.25 miles south, he decides to run for
only 50 minutes more. If Bob runs at a constant rate
of 8 minutes per mile, how many miles farther south
can he run and still be able to return to the parking lot
in 50 minutes?
(A) 1.5
(B) 2.25
(C) 3.0
(D) 3.25
(E) 4.75
SOLUTION
After running 3.25 miles south, Bob has been
running for (3.25)(8) = 26minutes. Thus, if t is the number of additional minutes
that Bob can run south before turning around,
then the number of minutes that Bob will run
north, after turning around, will be t + 26. Since
Bob will be running a total of 50 minutes after
the initial 26 minutes of running, it follows that
t + (t + 26) = 50, or t = 12. Therefore, Bob can run
south an additional 12 / 8 = 1.5 miles before turning around.
The correct answer is A.
My first concern is the calculation of (3.25)(8) = 26minutes. This is essentially saying Distance x Rate = time. That does not match Distance = Rate x Time??
My second conceern is the calculation of 12 / 8 = 1.5 miles. This is essentially saying Time / Rate = Distance. However, this does not match the Distance = Rate x time forumula?
Is there another formula? Or is my formula incorrect?? I'm confused
After driving to a riverfront parking lot, Bob plans to
run south along the river, turn around, and return to
the parking lot, running north along the same path.
After running 3.25 miles south, he decides to run for
only 50 minutes more. If Bob runs at a constant rate
of 8 minutes per mile, how many miles farther south
can he run and still be able to return to the parking lot
in 50 minutes?
(A) 1.5
(B) 2.25
(C) 3.0
(D) 3.25
(E) 4.75
SOLUTION
After running 3.25 miles south, Bob has been
running for (3.25)(8) = 26minutes. Thus, if t is the number of additional minutes
that Bob can run south before turning around,
then the number of minutes that Bob will run
north, after turning around, will be t + 26. Since
Bob will be running a total of 50 minutes after
the initial 26 minutes of running, it follows that
t + (t + 26) = 50, or t = 12. Therefore, Bob can run
south an additional 12 / 8 = 1.5 miles before turning around.
The correct answer is A.
My first concern is the calculation of (3.25)(8) = 26minutes. This is essentially saying Distance x Rate = time. That does not match Distance = Rate x Time??
My second conceern is the calculation of 12 / 8 = 1.5 miles. This is essentially saying Time / Rate = Distance. However, this does not match the Distance = Rate x time forumula?
Is there another formula? Or is my formula incorrect?? I'm confused
