Last week at a certain grocery store, 60 employees each worked 30 hours either at a cash register or stocking shelves. Of these employees, 1/5 worked at a cash register 20 hours, ¼ worked at a cash register 12 hours, 1/3 worked at a cash register 15 hours, and the remaining employees worked at a cash register 24 hours last week. What was the average (arithmetic mean) of the numbers of hours that these employees worked stocking shelves last week?

Choosing 14 suggests a miscalculation in determining the total hours worked at cash registers. The arithmetic mean should reflect the remaining hours after calculating the proper distribution of hours worked in both roles, which does not align with this figure based on the data provided.

This option also indicates an incorrect computation of total hours worked at cash registers, leading to an overestimate of the average hours spent stocking shelves. The average should account for the specific distribution of hours worked at cash registers, which does not support this value.

The selection of 16.4 represents a significant overestimation of the average hours. This figure fails to accurately correspond to the total hours worked at cash registers and does not consider the proper subtraction to find the hours spent stocking shelves.

Choosing 18 suggests a substantial misunderstanding of the distribution of work hours. This value implies that the employees spent far more time stocking shelves than what the calculations reveal, thus not aligning with the hour allocations provided in the scenario.