Final answer:
To find the indicated marginal cost, we need to take the derivative of y with respect to c, while keeping x and y constant. Plugging in the given values, we can then find the partial derivative of y with respect to c.
Step-by-step explanation:
Marginal cost is the additional cost of producing one more unit of output. It is calculated by taking the change in total cost and dividing it by the change in quantity. In this case, we are given the cost function c = 8x + 0.8y^2 + 2y + 700. To find the marginal cost (∂y/∂c), we need to take the derivative of y with respect to c, while keeping x and y constant. Plugging in x = 30 and y = 10 into the cost function, we can then find the partial derivative ∂y/∂c.