[GMAT math practice question]
There are 4 machines with the same work rate. If it took k hours for 3 machines to work and did k-2 hours for 4 machines when working together, what is the value of k?
A. 4
B. 5
C. 6
D. 7
E. 8
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There are 4 machines with the same work rate. If it took k
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Max@Math Revolution
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Total machine working hours will be the same for 3 machines and 4 machines.Max@Math Revolution wrote:[GMAT math practice question]
There are 4 machines with the same work rate. If it took k hours for 3 machines to work and did k-2 hours for 4 machines when working together, what is the value of k?
A. 4
B. 5
C. 6
D. 7
E. 8
Total machine hours with 3 machines = 3k
Total machine hours with 4 machines = 4(k-2)
3k = 4(k-2)
3k = 4k - 8
k = 8
Answer = (E) 8
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Max@Math Revolution
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=>
Work Amount = Number of machines * Work Rate * Time
If r is the machine's work rate, we have 3rk = 4r(k-2) or 3k = 4k -8.
Thus k = 8.
Therefore, E is the answer.
Answer: E
Work Amount = Number of machines * Work Rate * Time
If r is the machine's work rate, we have 3rk = 4r(k-2) or 3k = 4k -8.
Thus k = 8.
Therefore, E is the answer.
Answer: E
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Scott@TargetTestPrep
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Let the rate of each machine be r. We can create the equation:Max@Math Revolution wrote:[GMAT math practice question]
There are 4 machines with the same work rate. If it took k hours for 3 machines to work and did k-2 hours for 4 machines when working together, what is the value of k?
A. 4
B. 5
C. 6
D. 7
E. 8
(3r)k = (4r)(k - 2)
3k = 4k - 8
8 = k
Answer: E
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