NDA (II) 2022 General Ability Test · Question 126 of 150

Correct — C, 3. All three statements are the standard definitions, so the count is three. Physiological density does divide the total population by the cultivable area. Agricultural density does divide the agricultural population by the cultivable area. Population density, also called arithmetic density, does divide the total population by the total area. Notice that only the denominator changes between the first and the third — total area gives the plain persons-per-square-kilometre figure, while cultivable area gives a sharper measure of how many people each hectare of farmland has to feed.

• (a)1 — Answering one means judging two of the three definitions wrong. The usual reason for that is treating physiological density as a synonym for ordinary population density; the two differ only in what sits below the line, total area in one case and net cultivable area in the other, and both statements state that correctly.
• (b)2 — Answering two normally comes from rejecting statement 2 on the belief that agricultural density uses the whole population. It does not — the numerator is the agricultural population and the denominator the net cultivable area, which is exactly what the statement says.
• (d)None — This would require even statement 3 to be wrong, and statement 3 is simply the persons-per-square-kilometre figure that every census table reports. With all three definitions correct, 'None' cannot stand.

Three different ratios are used to measure how heavily people press on land, and they differ only in the numerator and denominator you choose. Arithmetic or population density spreads the whole population over the whole area. Physiological density spreads the whole population over only the land that can be cultivated. Agricultural density puts only the farming population over that same cultivable land. Since cultivable area can never exceed total area, physiological density is always at least as high as arithmetic density, and the gap between them measures how much of a country is desert, mountain, ice or built-up.

A how-many-statements item like this is answered by testing each line against a definition, not by hunting for a trick. All three lines here are textbook. The one place a careful reader might hesitate is statement 2, because some standard references define agricultural density using the rural population rather than the agricultural population; those are close in meaning, since the agricultural population is farmers and their dependants, and the exam's wording is the form used in Indian geography textbooks. Egypt is the classic illustration of why the distinction matters — almost everyone lives on the sliver of cultivable land along the Nile, so its physiological density is enormously higher than its arithmetic density.

• Population or arithmetic density = total population ÷ total land area.
• Physiological density = total population ÷ net cultivable area.
• Agricultural density = agricultural population ÷ net cultivable area.
• Because cultivable area is a subset of total area, physiological density is always greater than or equal to arithmetic density for the same region.

• Reading physiological density as a health or biology statistic; it is a land-based ratio.
• Swapping the numerators of physiological and agricultural density.
• Assuming a 'how many statements' item must contain at least one false statement — here all three are correct.

As a how-many-statements item, as a straight definition match, or as an applied question asking which country shows the widest gap between arithmetic and physiological density.

• practice — not a real PYQ

  Physiological density is obtained by dividing the total population by the

  • (a)total land area
  • (b)net cultivable area
  • (c)total urban area
  • (d)forest area

  Answer(b) net cultivable area — dividing by total land area instead would give ordinary arithmetic density.

• practice — not a real PYQ

  Which measure of density divides the agricultural population by the net cultivable area?

  • (a)Arithmetic density
  • (b)Physiological density
  • (c)Agricultural density
  • (d)Nutritional density

  Answer(c) Agricultural density — it narrows both the numerator and the denominator to the farming sector.