This problem consists of two separate problems using the price elasticity of demand concept.
Suppose that you know that the market demand curve for a product is given by the equation P = 100 – 2Q. Furthermore you know that initially 40 units are demanded in this market when it is in equilibrium. Then, some event causes the equilibrium to change so that only 35 units are demanded in this market. From this information you are asked to calculate the price elasticity of demand using the arc elasticity concept. Finally you are asked to identify whether demand is elastic, unit elastic, or inelastic when quantity changes from 40 units to 35 units.
Suppose you know that the price elasticity of demand for good X has a value of 2. Suppose that the price in the market is initially $10 and the quantity demanded is 100 units. If price in this market decreases by 10%, what will be the percentage change in the quantity demanded given the above information?