You need to use the formula for compound interest which is
A is the future value - in our case it is double what we started with.
P is the current value of the money (funds) for investment.
r (or i) is the rate of interest and is divided by 100 because it is expressed as a percentage which is any amount out of 100.
n is the number of years we are investing for.
The above formula is the standard formula and is used as is when compounding annually (once a year)Care to adjust the formula to allow for the quarterly compounding by dividing`r/100` by 4. If it was compounded annually you would divide by 12 and so on. Also multiply `n` by 4 - the same number as you divided `r/100` by.
We do not know `A` and we do not know `P` but as we are doubling our money we can express `A` in terms of `P. A=2P`
`therefore 2 = (1.015)^(4n)`
Use logs :
`log2= log 1.015^(4n)`
Simplify using the laws of logs :
`log2 = 4n log1.015`
`thereforelog2/log1.015 = 4n`
46.5555 / 4 = n
n= 11.639 years
`therefore`your money will double in 12 years (to the nearest year).