Source: GMAT Prep
If a certain wheel turns at a constant rate of x revolutions per minute, how many revolutions will the wheel make in k seconds?
A. 60kx
B. kx
C. x/k
D. x/60k
E. kx/60
The OA is E.
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If a certain wheel turns at a constant rate of x revolutions
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BTGmoderatorLU
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fskilnik@GMATH
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$$x\,\,{\rm{revol}}\,\,\, \leftrightarrow \,\,\,1\,\,\min $$BTGmoderatorLU wrote:Source: GMAT Prep
If a certain wheel turns at a constant rate of x revolutions per minute, how many revolutions will the wheel make in k seconds?
A. 60kx
B. kx
C. x/k
D. x/60k
E. kx/60
$$?\,\,=\,\,\# \,\,{\rm{revol}}\,\,{\rm{in}}\,\,k\,\,\sec $$
Trivial application of UNITS CONTROL, one of the most powerful tools of our method!
$$? = k\,\,\sec \,\,\left( {{{1\,\,\min } \over {60\,\,\sec }}} \right)\,\,\left( {{{x\,\,{\rm{revol}}} \over {1\,\,\min }}} \right) = \,\,\,{{kx} \over {60}}\,\,\,\,\left[ {{\rm{revol}}} \right]$$
This solution follows the notations and rationale taught in the GMATH method.
Regards,
Fabio.
Fabio Skilnik :: GMATH method creator ( Math for the GMAT)
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Hi All,
We're told that a certain wheel turns at a constant rate of X revolutions per MINUTE. We're asked for the number of revolutions that the wheel will make in K SECONDS. This question can be solved in a number of different ways, including by TESTing VALUES.
IF.... X=2 and K=60...
The wheel makes 2 revolutions per MINUTE and in 60 SECONDS it makes 2 revolutions.
Thus, we're looking for an answer that equals 2 when we TEST X=2 and K=60 into the answer. There's only one answer that matches...
Final Answer: E
GMAT assassins aren't born, they're made,
Rich
We're told that a certain wheel turns at a constant rate of X revolutions per MINUTE. We're asked for the number of revolutions that the wheel will make in K SECONDS. This question can be solved in a number of different ways, including by TESTing VALUES.
IF.... X=2 and K=60...
The wheel makes 2 revolutions per MINUTE and in 60 SECONDS it makes 2 revolutions.
Thus, we're looking for an answer that equals 2 when we TEST X=2 and K=60 into the answer. There's only one answer that matches...
Final Answer: E
GMAT assassins aren't born, they're made,
Rich
GMAT/MBA Expert
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Scott@TargetTestPrep
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Since k seconds is k/60 minutes, the wheel will make x * k/60 = xk/60 revolutions in k seconds.BTGmoderatorLU wrote:Source: GMAT Prep
If a certain wheel turns at a constant rate of x revolutions per minute, how many revolutions will the wheel make in k seconds?
A. 60kx
B. kx
C. x/k
D. x/60k
E. kx/60
Alternate Solution:
We can create a proportion: "x revolutions is to 60 seconds as q revolutions is to k seconds," and our goal is to solve for q:
x/60 = q/k
xk = 60q
xk/60 = q
Answer: E
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