Minute average

In a factory, four workers are assigned to complete an order received for dispatching 1400 boxes of a particular commodity. Worker A takes 4 minutes per box, Worker B takes 6 minutes per box, C takes 10 minutes per box, and D takes 15 minutes per box. Find the average minutes taken per box by the group of workers.

Correct answer:

b =  1.7143 min

Step-by-step explanation:

$b=\frac{1}{1/4+1/6+1/10+1/15}=\frac{12}{7}\text{min}=1.7143\text{min}$

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