Industrial consumption of power doubled from 2000 to 2010. Find the annual rate of increase in percent assuming it to be uniform over the years.
A. 5.6
B. 7.2
C. 10.0
D. 12.2
GATE 2014 · General Aptitude · Percentage · medium
Answer: Annual rate of increase = 7.2% (approximately). Answer: B.
Set up compound growth equation: P * (1 + r/100)^10 = 2P. Dividing both sides by P: (1 + r/100)^10 = 2.
Take the 10th root of both sides: 2^(1/10) = 2^0.1. Using log: 0.1 * log(2) = 0.1 * 0.30103 = 0.030103, so 10^(0.030103) = 1.07177.
Convert to percentage: r = (1.0718 - 1) * 100 = 0.0718 * 100 = 7.18%, which rounds to 7.2%.