3.73% would do it almost exactly:
Where p is the original investment and i is the rate of interest:
3p = p((1 + i/100) to the power of 30)
dividing by p gives ((1 + i/100) to the power 30) = 3
using logarithms (log 3)/30 = 1 + i/100
antilog (0.47712/30) = 1 + i/100
antilog 0.0159 = 1 + i/100
1.037299 = 1 + i/100
0.037299 = i/100
i = 3.7299
Later: I tested this on Excel with capital of 5000 and interest rate of 3.73% and after 30 years investment was worth 15000.35!
We still need to know how often the interest is compounded ... Weekly ? Daily ? Hourly ? What does "continuous" mean ?
the equation for compound interest is Pe^(rt) the principal you want in the end is twice that of the original 12,000 plugging in and solving you get 12,000=6000e^(.13t) t = 5.33 years
The Rule of 72 is a simple formula used to estimate the number of years required to double an investment based on a fixed annual rate of return. To use it, divide 72 by the expected annual interest rate (expressed as a whole number). For example, if your investment earns 6% annually, it would take approximately 72 ÷ 6 = 12 years to double your money. This rule provides a quick and easy way to gauge the impact of compound interest on investments.
Solve the following equation: (1 + x/100)8 = 3. That is, your money increases by a certain factor each year; the factor is the capital plus the percentage rate (divided by 100), and if you multiply the factor by itself 8 times, you get a factor of 3. To start solving this, take the 8th. root left and right.
Penalty interest is calculated from the required and projected balance
Approx 44.225 % The exact value is 100*[3^(1/3) - 1] %
It is approx 8.66%
(2)1/21 = 1.03356 (rounded)That's an annual interest of 3.356 percent.Let's try it:(1.03356)21 = 2.00009 on my calculator, which is pretty close.
390.45
(1+x)10 = 310 log(1+x) = log(3)log(1+x) = 0.1 log(3)(1+x) = 10[0.1 log(3)] = 1.116123x = .116123 = 11.61 percent
We still need to know how often the interest is compounded ... Weekly ? Daily ? Hourly ? What does "continuous" mean ?
A good jumbo CD rate would be over 5% and one must be careful to find out how often the interest will be compounded. Also important is the minimum investment amount that would be required.
Future Value = (Present Value)*(1 + i)^n {i is interest rate per compounding period, and n is the number of compounding periods} Memorize this.So if you want to double, then (Future Value)/(Present Value) = 2, and n = 16.2 = (1 + i)^16 --> 2^(1/16) = 1 + i --> i = 2^(1/16) - 1 = 0.044274 = 4.4274 %
If it is compounded annually, then: F = P*(1 + i)^t {F is final value, P is present value, and i is interest rate, t is time}.So if it triples, F/P = 3, and 12 years: t = 12, so we have 3 = (1 + i)^12, solve for i using logarithms (any base log will do, but I'll use base 10):log(3) = log((1+i)^12) = 12*log(1+i)(log(3))/12 = log(1+i).Now take 10 raised to both sides: 10^((log(3))/12) = 10^log(1+i) = 1 + ii = 10^((log(3))/12) - 1 = 0.095873So a rate of 9.5873 % (compounded annually) will triple the investment in 12 years.
the equation for compound interest is Pe^(rt) the principal you want in the end is twice that of the original 12,000 plugging in and solving you get 12,000=6000e^(.13t) t = 5.33 years
required rate of return is the 'interest' that investors expect from an investment project. coupon rate is the interest that investors receive periodically as a reward from investing in a bond
The Rule of 72 is a simple formula used to estimate the number of years required to double an investment based on a fixed annual rate of return. To use it, divide 72 by the expected annual interest rate (expressed as a whole number). For example, if your investment earns 6% annually, it would take approximately 72 ÷ 6 = 12 years to double your money. This rule provides a quick and easy way to gauge the impact of compound interest on investments.