Aaron will jog from home at x miles perr hour and then walk back home by the same route at y miles per hour. How may miles fromhome can Aaro jog so that he spends a total of t hours jogging and walking.
A. xt/y
B. x + t/xy
C. xyt/x+y
D. x+y+t/xy
E. y+t/x- t/y
Answer: C
Please explain reasoning
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Hi Oquiella,
This question can be solved by TESTing VALUES. I'm going to give you a couple of hints so that you can attempt this question on your own...
1) Since this question has so many variables, you want to make sure that the variables are easy to work with. Try using X = 3 miles/hour and Y = 2 miles/hour and set each distance at 6 miles.
2) You'll have to do some simple calculations to figure out the time traveled in each direction and the total time (T), which you'll need to answer the question.
3) TEST those values in the answer choices; you're looking for answer that equals 6.
GMAT assassins aren't born, they're made,
Rich
This question can be solved by TESTing VALUES. I'm going to give you a couple of hints so that you can attempt this question on your own...
1) Since this question has so many variables, you want to make sure that the variables are easy to work with. Try using X = 3 miles/hour and Y = 2 miles/hour and set each distance at 6 miles.
2) You'll have to do some simple calculations to figure out the time traveled in each direction and the total time (T), which you'll need to answer the question.
3) TEST those values in the answer choices; you're looking for answer that equals 6.
GMAT assassins aren't born, they're made,
Rich
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ceilidh.erickson
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I agree with Rich: testing values works well in this case. Most GMAT experts will consider testing values whenever there are variables in the answer choices.
However, the algebra on this problem isn't too hard to solve. You just have to be careful about the wording in this problem.
The question is asking "how many miles from home will Aaron jog" - in other words, the DISTANCE for ONE portion of his journey.
The trick is that the TIME is defined as "a total of t hours jogging and walking." We need to add the times for both portions.
I find that with RATE problems, using a chart helps to stay organized:
Now, fill in the variables given, using "d" for the distance in one direction that we're solving for:
It's clear now the the total time, t, is equal to the sum of the two individual times, d/x and d/y. Create an equation:
Now create a common denominator:
Add the fractions together:
Multiply both sides by xy:
factor out a d:
Divide both sides by (x + y):
The answer is C.
However, the algebra on this problem isn't too hard to solve. You just have to be careful about the wording in this problem.
The question is asking "how many miles from home will Aaron jog" - in other words, the DISTANCE for ONE portion of his journey.
The trick is that the TIME is defined as "a total of t hours jogging and walking." We need to add the times for both portions.
I find that with RATE problems, using a chart helps to stay organized:
Now, fill in the variables given, using "d" for the distance in one direction that we're solving for:
It's clear now the the total time, t, is equal to the sum of the two individual times, d/x and d/y. Create an equation:
Now create a common denominator:
Add the fractions together:
Multiply both sides by xy:
factor out a d:
Divide both sides by (x + y):
The answer is C.
Ceilidh Erickson
EdM in Mind, Brain, and Education
Harvard Graduate School of Education
EdM in Mind, Brain, and Education
Harvard Graduate School of Education
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Brent@GMATPrepNow
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Rich and Ceilidh have demonstrated the two methods (Algebraic and Input-Output) for solving a question type I call Variables in the Answer Choices.
If you'd like more information on these approaches, we have some free videos:
- Variables in the Answer Choices - https://www.gmatprepnow.com/module/gmat- ... /video/933
- Tips for the Algebraic Approach - https://www.gmatprepnow.com/module/gmat- ... /video/934
- Tips for the Input-Output Approach - https://www.gmatprepnow.com/module/gmat- ... /video/935
Cheers,
Brent
If you'd like more information on these approaches, we have some free videos:
- Variables in the Answer Choices - https://www.gmatprepnow.com/module/gmat- ... /video/933
- Tips for the Algebraic Approach - https://www.gmatprepnow.com/module/gmat- ... /video/934
- Tips for the Input-Output Approach - https://www.gmatprepnow.com/module/gmat- ... /video/935
Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
