21. What is the difference between change in demand and change in quantity demanded?

22. Explain the following statement: The only thing that can't cause a change in the demand for gasoline is a change in the price of gasoline.

23. Consider the following table:

Products	Production Rates	Production Rates	Production Rates	Production Rates	Production Rates
	A	B	C	D	E
X	5	10	15	20	25
Y	150	140	120	90	50

What are the Marginal Rate of Transformations (MRTs) from

A. A to B

B . B to C

C. C to D and

D. D to E?

24. Under what condition does a production possibility frontier take the shape of a straight line?

25. Explain why societies cannot make a choice above their production possibilities frontier and should not make a choice below it. 3