The number of units in inventory is , where is time in months.

Draw a table for the function at different values.

Graph the function:

Observe the graph:

The function is continuous each point except even integers.

The inventory is reach in beginning of a month period and it reaches at the end of month period.

Therefore, the company replenish its inventory for every two months.

Graph:

The function is continuous each point except even integers.

The company replenish its inventory for every two months.