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Bunuel
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Six machines, each working at the same constant rate 07 Dec 2022, 02:13
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Schachfreizeit
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Six 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?
A. 2
B. 3
C. 4
D. 6
E. 8

Let \(x\) be the time needed for 1 machine to complete the job, so rate of one machine is \(\frac{1}{x}\) (rate is the reciprocal of time) --> rate of 6 machines would be \(\frac{6}{x}\).

As \(job=time*rate\) --> \(1=12*\frac{6}{x}\) --> \(x=72\) days needed for 1 machine to complete the job.

To complete the job in 8 days \(\frac{72}{8}=9\) machines are needed.


Difference: 9-6=3.

Answer: B.

so if one machine would need 60 min, so 1/60 to get the job done, 6 machines would need 10 min, bc 6/60=1/10?
I don't understand the equation: 1=12*(6/x). Why does 12*(6/x) equals 1?
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1 there is the number of jobs done but ignore the formula for a moment.

If 6 machines need 12 days to complete a certain job, then 1 machine will need 6 times the days, so 6*12 = 72 days, no?
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Six machines, each working at the same constant rate 04 Sep 2023, 04:44
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#workers/Rate of worker = Proportion method.

6/(1/12)=x/(1/8)
6*12 = x*8
x=9
therefore
9-6= 3 (B is the correct option)
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Six machines, each working at the same constant rate 09 Sep 2023, 10:10
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Six 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?
SOLUTION:- (M1D1) = (M2D2)
6 * 12 = M2 * 8 ; where M2 is the number of machines required to complete the job in 8 days
M2 = 9
Addition machines required = 9 - 6 = 3
Hence B
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Six machines, each working at the same constant rate 17 Apr 2025, 02:56
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(N1 x T1 / W1) = (N2 x T2 / W2)

Consider Work = W1 = W2 = 1

(6 x 12 / 1) = (N2 x 8 / 1)

N2 = 9 machines

9 machines can complete work in 8 days

thus additional machine required = N2 - N1 = 9-6 = 3 machines

Ans B
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