Identify correct statements about age structure of population.
(A) Nigeria has triangular shaped age-sex pyramid.
(B) Australia's age-sex pyramid is bell shaped.
(C) Japan has a narrow base pyramid.
(D) Mexico has bell shaped age-sex pyramid.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (A), (B) and (C) only
The shape of an age-sex pyramid shows the birth and death rates of a population. A wide base means many children, that is, a high birth rate.
(A) Nigeria has triangular shaped age-sex pyramid. — True. Nigeria’s pyramid is triangular with a wide base, typical of less developed countries with high birth rates (an expanding population).
(B) Australia’s age-sex pyramid is bell shaped. — True. Australia’s pyramid is bell shaped and tapered towards the top. Birth and death rates are almost equal, so the population is nearly constant.
(C) Japan has a narrow base pyramid. — True. Japan’s pyramid has a narrow base and a tapered top, showing low birth and death rates (a declining population).
(D) Mexico has bell shaped age-sex pyramid. — False. Mexico’s pyramid would look the same as Nigeria’s, that is, triangular with a wide base, not bell shaped.
Note: This question is taken from the pre-rationalised NCERT book. The latest edition (2026-27) does not have this part. An extract of the pre-rationalised NCERT book is given below for the benefit of students.
Pre-rationalised NCERT: “Expanding Populations The age-sex pyramid of Nigeria as you can see is a triangular shaped pyramid with a wide base and is typical of less developed countries. These have larger populations in lower age groups due to high birth rates. If you construct the pyramids for Bangladesh and Mexico, it would look the same.” “Constant Population Australia’s age-sex pyramid is bell shaped and tapered towards the top. This shows birth and death rates are almost equal leading to a near constant population.” “Declining Populations The Japan pyramid has a narrow base and a tapered top showing low birth and death rates.” |