Question

An investment pays simple interest, and doubles in 7 years. What is the interest rate? Simple interest = A=P(1+rt)

Answer 1

looks like you just need to solve for "r"

Answer 2

What is my principle?

Answer 3

well. I guess is P and the balance after 7 years is A

Answer 4

I mean... we don't have constant value for those

Answer 5

With so little information how would I figure the interest rate? I am not familiar with the steps.

Answer 6

well years is "t"
and is pretty much all that's given

Answer 7

so do I put in any number?

Answer 8

so A=P(1+rt) => A=P(1+r(7))

Answer 9

I'd think not, I'd think you'd solve for "r" in A and P terms

Answer 10

A=P(1+r(7))
2=1(1+r(7))
How do I solve?

Answer 11

2? ... we dunno what A is
so is just A=P(1+r(7))

distribute the P and just do a linear equation simplification

Answer 12

I think I got it.

Answer 13

2=1(1+r(7)
2=(1+r7)
2-1=(1+r7)-1
1/7=r7/7
0.14285=r
thus the interest rate is 14.3%

Answer 14

hmmm I never did see the "2" or the "1"

Answer 15

I think you just take a number that doubles and it will always be 1.

Answer 16

I mean 1/7

Answer 17

hmmm

Answer 18

yeap.... you're right...

Answer 19

woohoo Thanks for helping. I don't know what I'd do without this site.

Answer 20

yw