total consumer surplus? so here is the question, i figured the answer is from subtracting each price of willing to pay from the actual market price and then adding them up equaling 65 as total consumer surplus. but in my book the answer is 80, i cant figure out how they got 80.
heres the question:
consider the market for used text books. use exhibit a-4 to calculate the total consumer surplus
http://books.google.com/books?id=qXJWU5kTZlUC&pg=PA97&lpg=PA97&dq=consider+the+market+for+used+text+books.+use+exhibit+a-4+to+calculate+the+total+consumer+surplus&source=bl&ots=SLVDb45sng&sig=2NsDHQCl6nIQNtvarS1CPdGRA7o&hl=en&ei=ktGZTrLnHNKssAKu9by8BA&sa=X&oi=book_result&ct=result&resnum=1&ved=0CBoQ6AEwAA#v=onepage&q&f=false
its at bottom of page exhibit a-4,
i already tried calculating it by measure the cs area but the question does not give me any quantities sold so that wont work,
please help thnx































