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Machine A produces pencils at a constant rate of 9000 [#permalink]
27 Dec 2007, 07:53
Machine A produces pencils at a constant rate of 9000 pencils per hour, and machine B produces pencils at a constant rate of 7000 pencils per hour. If the 2 machines together must produce 100.000 pencils and if each machine can operate for at most 8 hours, what is the least amount of time, in hours, that machine B must operate?