For each of the following cases, calculate the arc price elasticity of demand, and state whether demand is elastic, inelastic, or unit elastic.

a.When the price of milk increases from $2.25 to $2.50 per gallon, the quantity demanded falls from 100 gallons to 90 gallons.

b.When the price of paperback books falls from $7.00 to $6.50, the quantity demanded rises from

100 to 150

c.When the rent on apartments rises from $500 to $550, the quantity demanded decreases from 1,000 to 950.