Number of workers is irrelevant in calculation. It would be the hashing power of each machine.
Maybe try using a calc and divide to the time frames you want.
By using the hashing power you can see how much it would earn daily then divide by that.
ie 60mh would make 0.001260 Eth a day if u want 10hrs then 10/24x0.001260 would be the answer.

https://www.cryptocompare.com/mining/calculator/eth