bml1105 wrote:Machine A and Machine B are each used to manufacture 660 sprockets. It takes machine A 10 hours longer to produce 660 sprockets than Machine B. Machine B produces 10% more sprockets per hour than Machine A. How many sprockets per hour does machine A produce?
(A) 6
(B) 6.6
(C) 60
(D) 100
(E) 110
We can PLUG IN THE ANSWERS, which represent A's rate.
It is stated that B produces 10% more sprockets per hour than A.
Thus, when the correct answer choice is plugged in, B's rate will be 110% of A's rate.
The answer choices imply the following times for A:
660/6 = 110 hours.
660/6.6 = 100 hours.
660/60 = 11 hours.
660/100 = 6.6 hours.
660/110 = 6 hours.
It is stated that A's time is 10 hours longer than B's time.
Thus:
Answer choices D and E are not possible.
Answer choice C seems unlikely, since it implies that B's time is 1 hour.
Answer choice B implies that B's time = 90, a value that does not divide easily into 660.
The correct answer almost certainly is
A.
Answer choice A: A's rate = 6 sprockets per hour
Since A's time of 110 hours is 10 hours longer than B's time, B's time = 100 hours.
Thus, B's rate = 660/100 = 6.6 sprockets per hour.
(B's rate)/(A's rate) = 6.6/6 = 11/10 = 110%.
Success!
The correct answer is
A.
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