Akansha wrote: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
While I would recommend Anurag's solution, another approach is to plug in a value for the job.
Let job = 72 units.
Since the job takes 12 days, work per day = 72/12 = 6 units.
Since there are 6 machines, work per machine = 6/6 = 1 unit each day.
To complete the job in 8 days, work per day = 72/8 = 9 units.
Since 9-6=3 more units must be completed each day, number of additional machines needed = 3.
The correct answer is
B.
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