Final answer:
Using the midpoint method, the price elasticity of demand for pistachios was found to be 0.45, indicating inelastic demand between the price levels of $20 and $28 per ton.
Step-by-step explanation:
The main answer is that the price elasticity of demand for pistachios between the given price levels of $20 and $28 per ton is inelastic. This conclusion is drawn using the midpoint method to calculate the price elasticity of demand, which yields a value less than one, indicating inelastic demand. The detailed answer provided includes a calculation of percentage change in price and quantity based on the midpoint formula, which has led to a calculated elasticity of demand of 0.45. This value is considered inelastic because it is below one, and according to the convention, this negative elasticity is expressed as a positive number, for interpretational convenience.