WebCam Corp has a small factory to produce high quality webcams. At the curent production level, 1000 units per month, fixed costs are $10000 per month. If WebCam Corp. wants to increase production to above 1500 units per month, It will need to spend an additional $5,000 per month on additional fixed costs. ln contrast, if it reduces production to below 500 units per month, it will be able to reduce fixed costs to $7,500 per month. What is the relevant range for fixed costs at the current fixed cost level?