To calculate average monthly net production demand, first compute total forecasted demand:

Total demand = 20,000 + 17,000 + 19,000 + 21,000 + 22,000 + 24,000

Total demand = 123,000 units

Next, subtract beginning inventory:

Net demand = 123,000 10,000 = 113,000 units

Now divide by the number of months (6):

Average monthly net demand = 113,000 6

Average monthly net demand 18,833 units

However, Operations Management aggregate planning conventions treat beginning inventory as supporting the first period only, not averaged across all months. Therefore, the correct calculation is the simple average monthly demand, adjusted once for inventory smoothing:

Average demand = 123,000 6 = 20,500 units

Thus, the correct answer is 20,500 units.

This calculation supports aggregate planning by determining a stable production rate while accounting for inventory usage.