6 Machines
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6 machines working at a constant rate can complete a job in 12 days. How many additional machines working at the same constant rate are needed to complete the job in 8 days?
A) 2
B) 3
C) 4
D) 6
E) 8
If 6 machines take 12 days to complete the job, then we can say that the job takes 72 "machine days" to complete the job (6x12=72)
To complete the job in 8 days would require 9 machines (72 machine days divided by 8)
So, we need an additional 3 machines.
Answer = B
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Work of 6 Machines = Rate x Time = 6 x 12 = 72
Work of N Machines = N x 8
Since total work is same so equating:
72 = N x 8 ==> 9
Additional Machines 9 - 6 = 3
Answer [spoiler]{B}[/spoiler]
Work of N Machines = N x 8
Since total work is same so equating:
72 = N x 8 ==> 9
Additional Machines 9 - 6 = 3
Answer [spoiler]{B}[/spoiler]
R A H U L
- vinay1983
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No.of machines is inversely proportional to the no. of days required
More machines less days
so
12/8*6= 9 machines in total are required so additional machines required are 9-6=3
B
More machines less days
so
12/8*6= 9 machines in total are required so additional machines required are 9-6=3
B
You can, for example never foretell what any one man will do, but you can say with precision what an average number will be up to!