Question 229682
if you know your original investment amount (i.e. $1000) and you know your capital doubles every 6 years, how do you determine your interest rate percentage?
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If it's simple interest then

{{{I = Prt}}}

Then the interest in {{{6}}} years must equal the principle {{{P}}},
so we substitute {{{t=6}}} and {{{I=P}}} in the above equation
and get

{{{P = Pr(6)}}}
{{{P = 6Pr}}}

Divide both sides by {{{6P}}}

{{{(P)/(6P)=(6Pr)/(6P)}}}

{{{(cross(P)^1)/(6cross(P))=(cross(6P)r)/(cross(6P))}}}

{{{1/6=r}}}

{{{.16}}}{{{2/3=r}}}

{{{16&1/3}}}{{{"%"=r}}}

Edwin</pre>