Between two other points on the same demand curve, price rises from $120 to $130 and quantity demanded falls from 1,800 to 1,600. Using the midpoint method, what is the price elasticity of demand over this interval?

1. Percentage change in quantity: (1,600 minus 1,800) divided by the average of 1,600 and 1,800, which is 1,700, times 100. 2. That gives negative 200 divided by 1,700, times 100, which is about negative 11.76 percent. 3. Percentage change in price: (130 minus 120) divided by the average of 130 and 120, which is 125, times 100. 4. That gives 10 divided by 125, times 100, which is 8.0 percent. 5. Price elasticity of demand equals 11.76 divided by 8.0, read as a positive number, which is about 1.47. 6. Since 1.47 is above one, demand is elastic over this interval, confirming elasticity rose as price rose along the curve. 7. Option A's 0.45 is the elasticity of the lower-price interval computed earlier on the same curve. 8. Option B's 0.64 and option C's 2.83 both come from an unrelated table of alarm clock supply data. _Source: OpenStax Principles of Microeconomics for AP Courses (CC BY 4.0), Ch 5 "Elasticity", section 5.1 | Price Elasticity of Demand and Price Elasticity of Supply_