fomular of finding the growth percetage of something

Question

find the percetage in growth for a business that has an income of 2,000,000 in 2011 and registered 6,200,000 in 2013. How  do you calculate the percetage growth of such a case?

Answer 1

Growth = 6200000/2000000=3.1 in 2 years. That's 310%. So the amount of growth is 310%-100%=210%. (210% of 2M=4.2M and 2M+4.2M=6.2M.)

If the annual growth rate r is constant then the income in 2012 is 2000000(1+r).

And in 2013 it's (2000000(1+r))(1+r)=2000000(1+r)²=6200000, so:

(1+r)²=3.1, 1+r=√3.1=1.76, so r=0.76, that is, 76% per annum.