15 machines work at the same rate. Together, the 15 machines can complete an order in 8 hours. 3 of the machines break down after working for 6 hours.The other

Its 3 marks

1 Expert Answer

By:

Mark M. answered • 02/25/18

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The job takes 120 machine/hours (15 * 8)

In 6 hours the 15 machines do 90 machine hours.

That leaves 30 machine hours for the other 12 to do.

30 / 12 = 2.5 hours

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