Marginal Cost (MC) and Average Cost (AC)

The marginal cost (MC) is the additional cost incurred by producing one more unit of output. It is calculated by taking the change in total cost divided by the change in quantity of output.

The average cost (AC) is the total cost divided by the quantity of output. It represents the cost per unit of output.

Given that the marginal cost for the 9th unit of output is 20/- and the average cost at the same level of output is 15/-, we can analyze the relationship between MC and AC.

1. MC is greater than AC

If the marginal cost is greater than the average cost, it suggests that the cost of producing an additional unit is higher than the average cost per unit. This could occur due to various reasons such as diseconomies of scale or inefficient production methods.

In this case, since the marginal cost of producing the 9th unit is 20/- and the average cost at the same level is 15/-, we can conclude that MC is greater than AC.

2. MC is equal to AC

If the marginal cost is equal to the average cost, it implies that the cost of producing an additional unit is the same as the average cost per unit. This indicates that the firm is operating at its efficient scale.

However, based on the given information, the marginal cost of producing the 9th unit is 20/- and the average cost at the same level is 15/-. Therefore, we can conclude that MC is not equal to AC.

3. MC is less than AC

If the marginal cost is less than the average cost, it suggests that the cost of producing an additional unit is lower than the average cost per unit. This could occur due to economies of scale or efficient production methods.

In this case, since the marginal cost of producing the 9th unit is 20/- and the average cost at the same level is 15/-, we can conclude that MC is less than AC.

Conclusion

Based on the given information, we can conclude that the marginal cost (MC) for the 9th unit of output is greater than the average cost (AC) at the same level of output.