With reference to the year 2015-16, the percentage growth in the population of India by the year 2019-20 is

Population is recovered as Net National Income divided by Per capita Net National Income, since per capita income is total income shared over the population.

For 2015-16 this gives 122/95 = 1.28 and for 2019-20 it gives 177/132 = 1.34 as population indices.

The percentage growth is (1.34 - 1.28)/1.28 x 100, which works out to about 4.4%, so the answer is about 4.4%.

Net National Income is Net Domestic Product plus net factor income from abroad, measured after deducting depreciation.

The value 6.2% overstates the change by tracking income growth rather than the derived population ratio.

The value 7.1% wrongly compounds across years instead of taking a single ratio difference.

The value 3.1% understates it by comparing the per capita figures directly and ignoring total income.

Such data interpretation items reward first extracting the hidden variable, here population, before computing any percentage change.