Elasticity & Consumer Theory

A firm can increase total revenue by raising the price of a product with price-inelastic demand.. When demand is inelastic, quantity demanded falls proportionately less than the price rises, so revenue increases when price goes up.

Diminishing marginal utility causes consumers to be willing to pay less for additional units, producing a downward‑sloping demand curve.. As consumption rises, each extra unit yields less additional satisfaction, so consumers will only buy more at a lower price.

The correct answer is 0.8 because the quantity demanded falls by 20% and the price rises by 25%, resulting in an elasticity of 0.8. A diagram for this topic isn't available yet — the worked example below walks the same reasoning step by step.

• !Many students confuse the formula for price elasticity of demand or misinterpret the results, leading to incorrect conclusions about the elasticity of demand. Additionally, some students may incorrectly calculate the percentage changes in quantity and price.
• !Many students mistakenly believe that lowering the price will always increase total revenue, but this is only true for products with elastic demand. For price-inelastic demand, raising the price is the correct strategy to increase total revenue.
• !Students often treat any positive income elasticity as simply ‘normal’ and forget that values greater than one specifically denote luxury goods, while values between zero and one denote necessities.
• !Students often mistakenly think that utility stays constant or even rises with each additional unit, leading them to expect a flat or upward‑sloping demand curve.
• !Many students confuse the signs of cross-price elasticity, mistakenly assuming that a positive value indicates complements and a negative value indicates substitutes.

Answer each from memory — you'll see instantly whether you're right and why.

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