For a savings account paying 2.4% in which interest is compounded MONTHLY. FIND THE Time needed to double the initial investment of 10000 dollars. The answer is 28.9 years but WHY
1(1 + .024/12)^(12t) = 2 , any starting sum will do, I started with $1 and want to end up with $2
1.002^(12t) = 2
take log of both sides
log(1.002^(12t) ) = log2
rules of logs ....
12t log 1.002 = log 2
12t = log2/log1.002 = 346.92..
t = 346.92/12 = 28.91