Economists estimate price elasticities more precisely by using average price and quantity to compute percentage changes. Thus,

Using this formula, compute E for a popcorn price increase from 15 cents to 25 cents per ounce (Figure 4.5).

P,- P Q, + Q2 P, + P;' in absolute value E= Quantity Demanded Total Price Revenue $0.50 $0.50 0.45 2 0.90 0.40 1.60 0.35 2.10 Total rovenue Increasing es price drops. 0.30 2.40 0.25 12 3.00 0.20 16 3.20 0.15 20 3.00 Total revenue decreasing Es price drops. 0.10 25 2.50 0.05 30 1.50