Cases of product are conveyed to automatic palletizers for palletizing. Depending on the particular product and carton dimensions, the palletizer has to be reprogrammed by an operator. Typically, 25 pallet loads are completed before reprogramming is needed.

The reprogramming requires 4 minutes. The palletizer operates automatically for 40 minutes. The palletizer operator also must restock the machine with empty pallets; this can be done at any time during the last 10 minutes of the palletizer’s automatic run time;

restocking pallets requires 5 minutes. Travel time between palletizers, plus data entry in the computer system by the operator, requires 3 minutes. What is the maximum number of palletizers one operator can tend without creating idle time for the palletizer?