The following equation gives Jane's linear demand curve for visits to a nearby national park.  Q is the number of visits per week and P represents the price of a pass (price per visit):    P = -0.5Q + 10

a) Describe the demand curve given by (1), with price (P) on the vertical axis and quantity (Q) on the horizontal axis.

b) Suppose passes cost $5.  What is Jane's economic surplus for all the visits she makes at this price? 

c) Explain, in your own words, what economic surplus is.

d) If passes decline in price from $5 to $3, by how much does Jane's economic surplus change?  Is it less than or greater than in part (b)?  Explain why?