3. A downward-sloping demand curve exists for: A) a monopoly, but not for a perfectly competitive firm. B} a perfectly competitive firm, but not for a monopoly. C} both a monopoly and a perfectly competitive rm. D} either a monopoly or a perfectly competitive rm, depending on the costs of production. 4. Which of the following is {are} true? A) A monopoly rm is a price taker. E} MR :5- P if the demand curve is downward sloping. C) MR = MCI is a prot-maximizing rule for any rm. D) All of the above are true. 5. A demand curve that is linear and downward sloping: A} means that marginal revenue is equal to price. B} means that total revenue is always upward sloping. C} will result in a marginal revenue that is greater than price. D) has a price elasticity of demand that is equal to -1 when marginal revenue is equal to zero. 6. In the range of demand, total revenue with an increase in quantity. A) elastic; decreases B} elastic; does not change C} inelastic; decreases D) inelastic; does not change 7. Suppose that a monopolist increases production from 10 units to 1 1 units. If the market price declines from $20 per unit to $19 per unit, marginal revenue for the eleventh unit is: A) $1. B) $9. C) $19. D) $20