The population of India increased by 20% between 1989 and 1999. The population of India increased by a further 17% between 1999 and 2009.

Calculate the percentage by which the population of India increased between 1989 and 2009

40.4%

Explanation:

if n is the starting population of india in 1989,

1989 - 1999: the population increases by 20%. n × 120% = 1.2n

1999 - 2009: the population increases by another 17%. 1.2n × 117% = 1.404n

thus, the population increased from n to 1.404n, which is an increase of 0.404n.

0.404 = 40.4%. the percentage by which the population of india increased is 40.4%.

sorry, i'm not too sure if my answer is correct, but i hope this helps! :D