SOLUTION: I really need help with this question this is a two part question but I feel if you show me step by step how you got your answer then I will be able to try the other one. Find the

Algebra ->  Exponential-and-logarithmic-functions -> SOLUTION: I really need help with this question this is a two part question but I feel if you show me step by step how you got your answer then I will be able to try the other one. Find the      Log On


   



Question 998632: I really need help with this question this is a two part question but I feel if you show me step by step how you got your answer then I will be able to try the other one. Find the time it takes for $9,400 to double when invested at an annual interest rate of 13%, compounded continuously. Please show the years. I came up with approximately 5.3 years but the answer was wrong. thanks
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
rule of 72: doubles in 72/13; 72 divided by interest rate which would be about 5.54 years.The rule of 72 slightly overestimates the time to double. It applies in this case.
P=Poexp^rt
P/Po=2, which is doubling.
2=exp^rt
ln 2=rt
ln2/r=t
0.693/0.13 =t
t=5.33 years