Question

Simple Interest Question

Answer 1

Any principal amount invested at 5% annual interest takes 15 years to double. How many years does it take for the principal amount to triple?

Is there another way to solve this besides just plugging, for example, 500 for the initial amount and 1500 for the account balance, then solving for t?

Answer 2

Will show my work for that for the people that look this question up :P

\[A(t) = P(1 + r)^t\]
\[1500 = 500(1 + 0.05)^t\]
\[1500 = 500(1.05)^t\]
\[3 = (1.05)^t\]
\[\log_{1.05} (3) = t\]
\[t = 22.51708531\]

It would take approximately 22.5 years for the principal amount to triple.

Answer 3

I just want to know if there is another approach to this.

Answer 4

oh whoops sorry I was afk let me look

Answer 5

Wow. You had me on a leash.

Answer 6

wouldn't that equation be for compound not simple interest though?

Answer 7

Yeah, that's my bad. I'll change it.

Answer 8

The section I grabbed the question from was labeled simple interest ._.

Answer 9

(tbh I rarely use this equation since most problems want compound not simple)

Answer 10

actually I would modify this equation to be

A = P * (1+r) * T

to give the total amount of money in the account afterwards

Answer 11

Nvm I think your original method is the most straightforward way to do it

Answer 12

ok I'll be honest I'm kind of confusing myself with the arithmetic here

Answer 13

Well I have come to the same conclusion that you have. I will be on later tonight if you think of something, but I suppose it is the most straightforward way. I was just curious if there was a method which showed more understanding of the concept. But I suppose some questions are just simple, even if they do not declare themselves as such :)

Answer 14

yeah it's getting kind of late, my thinking gets fuzzy after midnight

g'night

Answer 15

Go to sleep shadow XD unless its early idek