Question

When working with compounded interest does doubling the time of an investment double the amount of interest earned

Answer 1

the equation for compound interest is

$A=P(1+r)^t$

we will see if it doubles or not

if t=1, we get A=P(1+r)

if t=2, we get A=P(1+r)^2

2(P(1+r))=P(1+r)^2 ?

2(1+r)=(1+r)^2 ?

2+r=r^2+2r+1

etc

when r=-1.618 or 0.618, then it doubles, but not when r is different things

not always

so no, it does not always double the amount of interest earned