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6 machines, each working at the same constant rate, together can complete a certain job in 12 days. How many additional machines, each working at the same constant rate, will be needed to complete the job in 8 days ?
2, 3, 4, 6, 8
see answer below
Ans = 3
Is there a technique to this problem type ? Applied the standard RT=W principles, but lost on this one..
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- jayhawk2001
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Let x be the time it takes for 1 machine to complete the job
6 * 1/x = 1/12
x = 72 days
n machines can complete the job in 8 days, so
n * 1/72 = 1/8
n = 9
Additional machines required = 9-6 = 3 days
6 * 1/x = 1/12
x = 72 days
n machines can complete the job in 8 days, so
n * 1/72 = 1/8
n = 9
Additional machines required = 9-6 = 3 days
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6 machines, each working at the same constant rate, together can complete a certain job in 12 days. How many additional machines, each working at the same constant rate, will be needed to complete the job in 8 days ?
2, 3, 4, 6, 8
This one is easy -
6 Machines - 1 Work - 12 Days
1 Machine - 1 Work - 12 * 6 Days
x Machines - 1 Work - 12 * 6 / x Days
12 * 6 / x = 8
Therefore x = 9
Thus 9 - 6 = 3 additional machines are needed
Hope this helps
2, 3, 4, 6, 8
This one is easy -
6 Machines - 1 Work - 12 Days
1 Machine - 1 Work - 12 * 6 Days
x Machines - 1 Work - 12 * 6 / x Days
12 * 6 / x = 8
Therefore x = 9
Thus 9 - 6 = 3 additional machines are needed
Hope this helps
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- Scott@TargetTestPrep
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We are given that six machines, each working at the same constant rate, together can complete a certain job in 12 days. Since rate = work/time, and if we consider work as 1, the rate of the six machines is 1/12.snapplesf wrote: --------------------------------------------
6 machines, each working at the same constant rate, together can complete a certain job in 12 days. How many additional machines, each working at the same constant rate, will be needed to complete the job in 8 days ?
2, 3, 4, 6, 8
We need to determine how many additional machines each working at the same constant rate will be needed to complete the same job in 8 days. In other words, we need to determine how many additional machines are needed to work at a rate of 1/8. Since each machine works at the same constant rate, we can use a proportion to first determine the number of machines needed to work at the rate of 1/8.
Our proportion is as follows: 6 machines is to a rate of 1/12 as x machines is to a rate of 1/8.
6/(1/12) = x/(1/8)
72 = 8x
x = 9
So, we need 9 - 6 = 3 more machines.
Answer: B
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