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Machines / Rate & Work Problem

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Machines / Rate & Work Problem

by daflower » Sun Jul 18, 2010 11:52 am
Need some help on this problem:

If 6 machines each working at a constant rate work together to complete a job in 12 days. How many additional machines are needed (working at the same rate) to complete the job in 8 days.

a) 2
b) 3
c) 4
d) 6
e) 8

Would really appreciate if anyone can explain how to solve this problem,
thanks!
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by aloneontheedge » Sun Jul 18, 2010 11:55 am
daflower wrote:Need some help on this problem:

If 6 machines each working at a constant rate work together to complete a job in 12 days. How many additional machines are needed (working at the same rate) to complete the job in 8 days.

a) 2
b) 3
c) 4
d) 6
e) 8

Would really appreciate if anyone can explain how to solve this problem,
thanks!
6*12/8 = x
x = 9
x = 9-6 = 3
pick B
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by daflower » Sun Jul 18, 2010 12:05 pm
Actually still confused.

If 6 machines are doing the work in 12 days.

Can we say that they are completing the job at a rate of
6 machines / 12 days = 1 machine / 2 days?
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by aloneontheedge » Sun Jul 18, 2010 12:12 pm
daflower wrote:Actually still confused.

If 6 machines are doing the work in 12 days.

Can we say that they are completing the job at a rate of
6 machines / 12 days = 1 machine / 2 days?
I did not get wat u r trying to say
6 machines = 12 days
In 1 day work done 6/12= 1/2
Or remember this formula
X*D1*w2*E1 = Y*D2*W1*E2
X ,Y= number of people
D1 n D2 are days
W1,w2 = work
e1 n e2 are efficiencies.
Try to apply the formula in above case. (w1= w2 in the above case as work is same)
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