Problema Solution
The income of Anny's family in 2008 is $65000. From 2008 to 2011, the income of the family increased by 20% per year. What's the total amount of income of Anny's family from 2008 to 2011?
Answer provided by our tutors
the income in 2008 is $65,000
the income in 2009 is 65,000 + 0.20*65,000 = 65,000*1.20
the income in 2010 is 65,000*1.20 + 0.20*65,000*1.20 = 65,000*(1.20^2)
the income in 2011 is 65,000*(1.20^2) + 0.20*65,000*(1.20^2) = 65,000*(1.20^3)
65,000 + 65,000*1.20 + 65,000*(1.20^2) + 65,000*(1.20^3) =
= 65,000(1 + 1.20 + 1.20^2 + 1.20^3) = 65000*5.368 = $348,920.00
the total amount of income of Anny's family from 2008 to 2011 is $348,920.00.