Suppose the demand curve for a product is given by Q =10 -2P +PS, where P is the price of the product and PS is the price of a substitute good. Suppose the price of the substitute good is $2.00, and P=$1.00. What is the price elasticity of demand? (answer with decimal number like 0.5) 10.0 x The following table shows the average retail price of butter and the Consumer Price Index from 1980 to 2010, scaled so that the CPI=100 in 1980. 1980 1990 2000 2010 CPI 100 158.56 208.98 218.06 Retail price of butter $1.88 $1.99 $2.52 $2.88 (salted, grade AA, per lb.) The real price of butter in 1980 dollars in 1990 is $ 1.26 The real price of butter in 1980 dollars in 2000 is $ 1.21 The real price of butter in 1980 dollars in 2010 is $ 1.32 What is the percentage change in the real price (1980 dollars) from 1980 to 2000? % 0.05