Simple Interest Question

8 months ago

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?

8 months ago

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.

8 months ago

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

8 months ago
Vocaloid:

oh whoops sorry I was afk let me look

8 months ago

Wow. You had me on a leash.

8 months ago
Vocaloid:

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

8 months ago

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

8 months ago

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

8 months ago
Vocaloid:

|dw:1508212574583:dw|

8 months ago
Vocaloid:

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

8 months ago
Vocaloid:

actually I would modify this equation to be A = P * (1+r) * T to give the total amount of money in the account afterwards

8 months ago
Vocaloid:

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

8 months ago
Vocaloid:

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

8 months ago

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 :)

8 months ago
Vocaloid:

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

8 months ago
Bearclaws72:

Go to sleep shadow XD unless its early idek

8 months ago