Explanation : Price elasticity of demand is the sensitivity measure of the quantity demanded (Q) for a product/service as a result of change in price (P) of the same product/service. Mathematically, the price elasticity (PE) of demand for a given product/service is defined as the percentage change in quantity demanded caused by a per cent change in price: Intuitively, the price elasticity is generally negative due to the negative relationship between the price and quantity demanded.