A manufacturer discovers that raising the price of his product from ₦500 to ₦600 leaves total revenue unchanged. The price elasticity of demand over this range is

When total revenue remains constant after a price change, the percentage increase in price is exactly offset by an equal percentage decrease in quantity demanded, giving a price elasticity of demand equal to 1 (unitary elasticity). At unitary elasticity, PED = 1, meaning TR = P × Q is constant at all points along that portion of the demand curve.