Q.At the market price of Rs 10, a firm supplies 4 units of output. The market price increases to Rs 30. The price elasticity of the firm's supply is 1.25. What quantity will the firm supply at the new price?

Price Elasticity of Supply: From the Market to the Formula

Imagine you run a small bakery. One morning, a sudden wedding order comes in — customers are willing to pay double your usual price for 100 extra loaves of bread. Can you instantly produce those 100 loaves? Probably not. You have limited ovens, a fixed amount of dough prepared, and only two hands. You might manage 20 extra loaves by working faster, but 100 is impossible today.

Now imagine the same order comes, but you have a month's notice. You can hire extra help, buy more flour, and even rent another oven. Suddenly, producing 100 extra loaves is easy.

This difference — how much quantity supplied changes when price changes — is exactly what Price Elasticity of Supply (PES) measures.

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The Precise Meaning

Price Elasticity of Supply tells us the percentage change in quantity supplied divided by the percentage change in price. It answers: "If the price rises by 1%, by what percentage will sellers increase the quantity they offer?"

Where:

• $E_s$ = Price Elasticity of Supply
• $\% \Delta Q_s$ = Percentage change in quantity supplied
• $\% \Delta P$ = Percentage change in price

Since supply curves are upward-sloping (higher price → higher quantity supplied), $E_s$ is always positive. A value of 2 means a 1% price rise leads to a 2% increase in quantity supplied. A value of 0.5 means only a 0.5% increase.

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Why It Matters: The Time Factor

The bakery example reveals the single most important determinant of PES: time. …