Question 752290
20 workers task 12 hours
1 worker  task {{{12*20}}} hours.
Rate for 1 worker is {{{1/240}}} tasks per hour.


Now you have 30 workers.  Rate?  Reciprocal?


Rate of each worker is additive as more workers are placed to work.

30 workers each at {{{1/240}}} task per hour means {{{highlight(30*(1/240))}}} task per hour.  FIND RECIPROCAL for how many HOURS per TASK.




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In fact, 8 hours for 30 workers to do the task.