Consider the decadal Census data given below: Year Population (in millions) 1961 10.7 1971 14.3 1981 16.2 1991 18.9 The above data refer to which one of the population by religion groups?

Answer: (c) Christians

Christians: 10.7 million (1961), 14.2 (1971), 16.2 (1981), about 19 (1991). The series fits.

The idea

A census time series must be matched using both its scale and its reference years. Percentages and absolute numbers are different clues. Comparisons also require the same geographical coverage; excluded areas can make apparently similar census totals differ.

Why the others are wrong

(a) Sikhs were about 7.8 million in 1961 and 16.3 million in 1991: the series does not fit.

(b) Jains are only a few million.

(d) Buddhists were about 3 to 6 million in these years.

The trap

Christians are close in size — check the 1961 figure.

Also know

Religion-wise population is a census category, distinct from language, caste and nationality. A group’s population can increase while its percentage falls if the total population grows faster. As of Census 2011, Sikhs were about 1.7% and Christians about 2.3% of India’s population; these later shares do not settle an earlier numerical series.