if the output is 10 and the total cost is 290 what is the marginal cost?

Answer 1

Insufficient data.

Marginal costing requires that you know the cost of producing one more unit. That is , the "variable cost" of producing one more unit. Marginal costing is not concerned with fixed costs as they are considered "sunken". If Total cost includes fixed costs, then you cannot calculate the marginal cost from this information.
If Total cost does not include fixed costs, then the cost of producing one more unit would be 290 (the marginal cost of producing one more unit)