Arrange the steps for calculating the price elasticity of demand using the midpoint (arc) method in sequential order.

### The order 1. **Find the change in the dependent variable**: subtract its initial value from its new value. 2. **Find the change in the independent variable**: calculate its change over the same interval. 3. **Express each change as a percentage of its initial value**: this puts the two variables on a comparable proportional scale. 4. **Divide the percentage change in the dependent variable by the percentage change in the independent variable**: this gives arc elasticity over the interval. ### The concept Arc elasticity measures responsiveness between two observed points. Point elasticity instead uses derivatives to measure responsiveness at a particular point on a curve. Both compare proportional changes, but they describe different locations or intervals. ### Terms - **Arc elasticity**: elasticity measured over a finite interval between two observations. - **Point elasticity**: elasticity measured at a particular point using the derivative of a function. ### Remember Convert both changes to percentages before taking their ratio.