For smart phone demand, price rises from $90 to $100 and quantity demanded falls from 2,400 to 2,200. Using the midpoint method, what is the price elasticity of demand over this interval?

1. Percentage change in quantity: (2,200 minus 2,400) divided by the average of 2,200 and 2,400, which is 2,300, times 100, is about negative 8.70 percent. 2. Percentage change in price: (100 minus 90) divided by the average of 100 and 90, which is 95, times 100, is about 10.53 percent. 3. Price elasticity of demand equals 8.70 divided by 10.53, read as a positive number, which is about 0.83. 4. Since 0.83 is below one, demand remains inelastic at this point on the curve, though closer to unitary than the lowest-price interval. 5. Option D's 0.45 was the elasticity at the lowest prices on the same curve. 6. Options C and A belong to unrelated intervals, not this one. _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_