- AThe self-service counters cost more to install than an ordinary counter staffed by a cashier
- BThe counters would be bought from a supplier the chain has not dealt with before
- CSome of the chain's stores hold more aisles than others
- DIn the busiest hours almost every customer is pushing a full trolley, and a shopper with a full trolley takes appreciably longer at a self-service counter than a trained cashier takes
Step-by-Step Solution
The waiting time falls only if the new counters clear customers faster than the old ones. If the very customers who crowd the peak hours are slower at a self-service counter, the extra counters add capacity of the wrong kind and the queue need not shorten at all. Installation cost, the identity of the supplier and the size of individual stores leave the service rate untouched.
Answer: D) In the busiest hours almost every customer is pushing a full trolley, and a shopper with a full trolley takes appreciably longer at a self-service counter than a trained cashier takes