Question

Suppose you want to remove fish of an exotic species that have illegally been introduced into a lake. There are two possible removal methods. The marginal cost function of the first method is $7x, where x is the number of fish removed using this method, and the marginal cost function of the second method is $9y, where y is the number of fish removed using this method.

Ecologists have determined that 144 fish need to be removed, so x + y = 144. How many fish should be removed using the first method (that is, what should x be) in order to remove the 144 fish cost-effectively? (Hint: Consider what the second equimarginal principle is about.)

Answer 1