NCERT Solutions for Class 9th Social Science Chapter 9 Other Determinants of Demand — LET'S EXPLORE

Book page 200 Updated on2026-09-08

Q1.

Create your own demand schedule for buying notebooks at different prices. At what price would you buy the most? At what price would you stop buying altogether? What could be the reason behind your choices?

Answer

Method. Fix a set of prices for one notebook — say ₹120, ₹90, ₹60, ₹30 and ₹10 — and against each write, honestly, how many notebooks you would buy in a school year at that price and no other. Keep everything else constant: the same pocket money, the same number of subjects, the same quality of notebook. Then plot price on the y-axis and quantity on the x-axis and join the points.

What a good answer must contain: (i) quantity rising as price falls, never the reverse; (ii) a price at which you buy the most — usually the lowest price on your list; (iii) a price at which your quantity falls to zero, or to the bare minimum your school demands; and (iv) reasons drawn from the chapter — purchasing power, diminishing marginal utility, and substitutes.

Sample answer:

Price of one notebook	Number I would buy in a year	My reason
₹120	2	Only for the two subjects that need a thick notebook; I would reuse old ones for the rest
₹90	4	Enough for the main subjects
₹60	7	One for every subject
₹30	10	One per subject plus rough work and a diary
₹10	14	I would keep spares and share with my cousin

I buy the most at ₹10 — the lowest price on my list
I would stop buying altogether at about ₹200 — my whole month's pocket money for one notebook
Fall in price ₹120 → ₹10 = ₹110 · Rise in quantity 2 → 14 = 12 notebooks

The three reasons behind the pattern, in the chapter's own terms:

Purchasing power. My pocket money is fixed, so at ₹120 each I simply cannot afford many; at ₹10 the same money stretches much further.
Diminishing marginal utility. The first notebook is essential, the twelfth is a spare I may never open — so I will only take it if it is very cheap.
Substitutes. Above about ₹200 I would use loose sheets in a file, or write on both sides of old notebooks. When a substitute becomes relatively cheaper, demand shifts to it — exactly as the chapter says of tea and coffee.

Check it yourself: if your table shows quantity rising as price rises, something else has crept in — usually a change in your income or in what you need. A demand schedule holds everything except price constant.

Q2.

Ask your family members if they postponed or advanced buying any product because of future expectations of changes in price?

Answer

Method. Ask two or three family members one clear question: “Was there something you deliberately bought earlier than you needed to, or waited longer to buy, only because of what you expected the price to do?” For each answer, note four things — the product, whether they advanced or postponed, what they expected the price to do, and what actually happened. Do not count purchases delayed for lack of money; that is a change in purchasing power, not in expectations.

What a good answer must contain: at least one case of each kind (postponed and advanced), the expectation that caused it, and the link back to the chapter's rule — “If consumers expect prices to fall, they postpone purchases, decreasing present demand. If they expect prices to rise, they buy immediately, increasing present demand.”

Sample answer:

Family member	Product	What they did	The expectation behind it
My father	A washing machine	Postponed from September to the Diwali sale	He expected festival discounts — the chapter's own example of delaying durables before Diwali
My mother	Cooking oil and pulses	Advanced — bought a larger tin in one go	Neighbours said prices would rise after the rains damaged the crop
My elder sister	A mobile phone	Postponed by two months	A new model was about to be launched, which usually brings the older model's price down

What the exercise shows: demand today is shaped by beliefs about tomorrow. Nothing about the washing machine changed in September — not its price, not the family's income — yet the family's demand for it in September was zero, because they expected a better price in November. This is one of the clearest cases of a determinant that shifts the whole demand curve without the current price moving at all.

Did you know? Sellers behave the same way. Page 203 gives the mirror image: potato wholesalers who expect prices to rise “might hold back supply now to sell later at higher prices.” When both sides act on the same expectation, the expectation can bring about the very price rise people were expecting.

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