Use the general relationship between marginal and average values to explain why a marginal cost curve must intersect an average total cost curve and an average variable cost curve at their minimum points

What will be an ideal response?

The relationship between marginal and average values can be stated as follows: if the marginal value is below the average value for a variable, it pulls the average value down and if the marginal value is above the average value, it pulls the average value up. Applying this to cost curves, if average total cost is falling, marginal cost must lie below average total cost. If average total cost is rising, marginal cost must lie above average total cost. Therefore, the marginal cost curve must intersect the average total cost curve at its minimum point. The same principle applies to the average variable cost curve.