At a price of $200, 8000 units are sold. at a price of $220, 6400 units are sold.
1. calculate the arc elasticity of demand
2. construct the demand equation. use midpoint price and quantity (p=210, q=7200), and the elasticity you have just calculated. Assume the demand equation takes the form Q= a+bP. Also recall that E=b(P/Q)