## anonymous 4 years ago find the amount of time in years that it will take an investment of \$1000 to double at 8%interest compounded continuosly. (hint A=Pe^rt

1. anonymous

Hi @CesarLovesNadia - so you know the formula you need to use, correct? Are you able to put them together?

2. anonymous

no im not thats why its here i need help

3. anonymous

No problem, so the interest formula for compound interest is what you have listed. So, A is the number we are looking for, we have the rest. So, A = P (principal amount) x e (Napier's #, roughly 2.7183) ^ r (interest rate) x t (number of years). So, how about you try and put in the numbers you know, and I can help you with anything you don't understand?

4. anonymous

For the 'e' - your calculator will actually have this number built in, so don't worry about it for now :)

5. anonymous

6. anonymous

how many years would it be?

7. anonymous

@CesarLovesNadia - You have to learn how to do these problems - I'm not here to give you the answer. I WILL help you get there though, I promise. Can you try and put the variables from the word problem into the equation now?

8. anonymous

i diid i put 1000*2.7183^(0.08*1)

9. anonymous

it came out to be like 1000 something

10. anonymous

No worries - and good start. The problem states that you need to find the time, t, for your money to double. Therefore, you know that A = 2xP = 2000. So, your equation looks like this: $2000 = 1000*e^(.08*t)$

11. anonymous

so then wait

12. anonymous

the answer would be 2000 then?

13. ParthKohli

Colm, it'd be $$2000 = 1000 \times e^{(0.8 \times t)}$$ Sorry for interfering, guys.

14. anonymous

thanks

15. ParthKohli

@CesarLovesNadia You should appreciate Colm for helping you :) P.S. He's the major part behind OpenStudy ;)

16. anonymous

Heh, that's what I was writing - guess it showed up wrong. And no, @CesarLovesNadia you need to find the TIME, t in this equation, right? "find the amount of time in years"

17. anonymous

but what is it then?

18. anonymous

just help me and give me the answer

19. anonymous

@CesarLovesNadia - sorry, but you should read the Code of Conduct ( http://openstudy.com/code-of-conduct) - we don't just give the answer. I can help you understand it though :) So now, you have to solve for T in that equation I and Parth just gave you. Can you start that?

20. anonymous

so would it be 2?

21. anonymous

is it 2?

22. ParthKohli

Heh—don't give me the credit. Keep it on, guys!

23. anonymous

help me with another one

24. anonymous

Given your equation 2000 = 1000 x e^(.08xT) We divide both sides by 1000 to give us this: 2 = e^(.08xT)

25. ParthKohli
26. ParthKohli

Your Math is pretty good, Colm!

27. anonymous

@CesarLovesNadia - you'll probably want to use that link to get the real answer. Hint - it's not two.