NCERT Solutions for Class 9th Social Science Chapter 9 Market Equilibrium — LET'S ANALYSE
Book page 204 Updated on2026-09-08
Q1.
Using data from Table 9.3, plot the demand and supply curve at the three prices, i.e., ₹40, ₹100, and ₹150. Identify and mark excess demand and supply on the graph. Think about how equilibrium could be reached in these scenarios.
Answer
Start by setting the table out as three pairs of points, then read the gap at each price. Table 9.3 gives:
Price (₹)
Qd (kg)
Qs (kg)
Gap
Outcome
40
38
6
38 − 6 = 32 kg short
Qs < Qd → Excess Demand
100
12
12
12 − 12 = 0
Qs = Qd → Market Equilibrium
150
8
43
43 − 8 = 35 kg extra
Qs > Qd → Excess Supply
Equilibrium price = ₹100 and equilibrium quantity = 12 kg, exactly as the table's last row states.
Table 9.3 plotted. The purple bar at ₹40 is the 32 kg shortage; the red bar at ₹150 is the 35 kg surplus. Both gaps close as the price moves towards E.
How equilibrium is reached in each scenario.
At ₹40 — a shortage of 32 kg. Thirty-eight kilograms are wanted and only six are on offer. Buyers who cannot get mangoes offer more than ₹40; sellers, seeing they can sell everything instantly, raise the price. As the price rises, two things happen together — some buyers drop out (a movement up along the demand curve, from 38 kg towards 12 kg) and sellers bring more to market (a movement up along the supply curve, from 6 kg towards 12 kg). The gap narrows from both ends and closes at ₹100.
At ₹150 — a surplus of 35 kg. Forty-three kilograms have been brought but only eight are wanted. The unsold fruit will spoil, so sellers cut the price. Now the falling price brings buyers back (down along the demand curve, from 8 kg towards 12 kg) and discourages sellers (down along the supply curve, from 43 kg towards 12 kg). The surplus disappears at ₹100.
At ₹100 — no gap. Everyone who is willing to pay ₹100 gets mangoes and everyone willing to sell at ₹100 sells them. Nobody has a reason to change the price, so it stays — the market is ‘cleared’.
Why the adjustment always works in the same direction: a shortage puts the pressure on buyers, who compete by offering more, and a surplus puts the pressure on sellers, who compete by asking less. In both cases the price moves towards the one level at which neither side is left disappointed.
Tip while plotting: the three demand points and the three supply points in Table 9.3 do not fall on perfectly straight lines, so join them as smooth lines through the plotted points rather than forcing a ruler through them. What matters is that D slopes downward, S slopes upward, and they cross at (12 kg, ₹100).