The following data represent a personal income tax schedule. Answer the question on the basis of this information. Refer to the below table. If income increases from $15,000 to $30,000, the marginal tax rate is:

Assume that the demand curve for sunblock is linear and downward sloping. Which of the following statements about the slope of the demand curve for sunblock and the price elasticity of demand for sunblock are true?

A) The slope is constant, but the price elasticity of demand is not constant at all points along the demand curve for sunblock. B) The slope of the demand curve for sunblock is constant and equal to zero; demand is perfectly inelastic. C) The slope is not constant, but the price elasticity of demand is constant at all points along the demand curve for sunblock. D) The slope and the price elasticity of demand are constant at all points along the demand curve for sunblock.

As output is expanded, if marginal cost (MC) is less than average total cost (ATC),

a. ATC must be at its minimum. b. ATC must be at its maximum. c. ATC must be decreasing. d. the firm must be earning economic profit.