2025 CSAT — Q71

Locate. This asks for the central idea — the passage’s load-bearing point — so find what its mechanism is built to show. The whole passage explains that one inflation number is an aggregate hiding very different price rises across items and across classes (poor/middle/rich baskets differ “vastly”). The point of all that machinery is that the single number misrepresents the individual case. That is the anchor.

Test — the thesis, not a detail; and check the fit. The key must state that the aggregate fails to measure the price rise of an individual item/consumer. (b) — “the present calculation of inflation rate does not correctly measure price rise of individual item/commodity” — is exactly the consequence the passage builds to.

Eliminate by anatomy. (a) is both outside the passage and too strong — “use WPI exclusively… CPI done away with” is a prescription the passage never makes; it explains why both are aggregates, not which to scrap. (c) is out of scope — “under-presents services” picks one word (“services”) and invents a claim the passage doesn’t make. (d) over-states the case — “not really of any use to anybody” is an absurd absolutism; the passage critiques the aggregate’s precision, not the value of inflation data. Key: (b).

“A single number for inflation is an aggregate across different commodities and services — the price rise differs for different items of consumption… The consumption basket is vastly different for the poor, the middle classes, and the rich. Hence, the CPI is different for each of these classes and a composite index requires averaging the baskets.” The crux is that a single aggregate inflation number fails to capture the price rise of individual items/consumers — (b).

The passage explains that a single inflation figure is an aggregate built by weighting many items, that people’s consumption baskets differ “vastly” by class, and that “a composite index requires averaging the baskets.” The crucial message is that this single aggregate does not accurately measure the price rise faced by an individual item or consumer.

(b) states this. Answer: (b).

Three distractors share the over-claim anatomy: (a) prescribes scrapping CPI, (d) dismisses inflation data wholesale, (c) invents a services claim. The passage’s actual, measured point is narrower and sharper — an aggregate hides individual variation. On a central-idea question, the key restates the author’s analytical point at its real scope; it does not turn a measurement critique into a policy demand or a nihilistic dismissal.