SOLUTION: If a sum of 12000 doubles in 5 years at compound interest basis.Then what will be the amount after 20 years, if compounded annually?

Question 141900: If a sum of 12000 doubles in 5 years at compound interest basis.Then what will be the amount after 20 years, if compounded annually?
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
If a sum of 12000 doubles in 5 years at compound interest basis.
:
Find the interest rate of this amt doubling in 5 yrs, compounded annually
12000*(1+r)^5 = 24000
:
(1+r)^5 = ; divided both sides by 12000
(1+r)^5 = 2
Use the log equiv of exponents:
5*log(1+r) = log(2)
log(1+r) =
log(1+r) = .0602
:
Find 10^x of both sides:
1+r = 1.1487
r = 1.1487 - 1
r = .1487 or 14.87% interest to double your money in 5 years
:
:
Then what will be the amount after 20 years, if compounded annually?
A = 12000(1.1487)^20
A = $192,005.50 in 20 years at this interest.
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