4. A firm operates with a Fixed Cost of $100. Use the cost data provided below to determine the Average Total Cost (ATC) at an output of 5 units.
| Output (Q) | Total Cost (TC) | Average Variable Cost (AVC) | Marginal Cost (MC) |
| --- | --- | --- | --- |
| 0 | $100 | -- | -- |
| 4 | -- | $60 | -- |
| 5 | -- | -- | $90 |
The Average Total Cost (ATC) for producing 5 units is: ____(4)____