5. (a) Without the presence of "scarcity", a problem cannot be considered as an economic problem. Can a design an engine problem that gives 100 miles per gallon be considered as an economic problem? Why or why not? (b) Why is a diamond which is not essential for human existence valued more than water which is essential for human life? Is this a "paradox" our values? (c) What do you think is the methodological difference between studying physics and economics; and philosophy and economics?

BONUS Does opportunist cost always have to be positive?