Based on the above table, which shows the firms and sales in an industry, what is the four-firm concentration ratio?

If a monopolist's marginal revenue is $3.00 and its marginal cost is $4.50, it will increase its profits by:

A. reducing output and raising price. B. reducing both output and price. C. increasing both price and output. D. raising price while keeping output unchanged.

If you receive $18 worth of pleasure from the first hole of golf played and your additional pleasure from succeeding holes drops $1 for each hole played, if the cost per hole is zero, how many holes of golf will you play?

A. 19 B. 18 C. 17 D. 16