The ________ curve describes the relationship between tax rates and tax revenue.

Which of the following statements is true?

a. The Phillips curve has always been stable. b. If the Phillips curve shifts outward to the right this illustrates a greater tradeoff between unemployment and inflation. c. Keynesian economics assumes a vertical Phillips curve. d. According to the natural rate hypothesis the Phillips curve is downward sloping. e. All of these.

Excluding criminal activities, the underground economy in the United States is equivalent in value to approximately what percentage of the GDP?

a. 10 to 15 percent b. 20 to 25 percent c. 30 to 35 percent d. not determinable