Question 1203682
<pre>
It more than doubled in 12 years, so it won't take that
long to double.

{{{A=P(1+r/n)^nt}}}

{{{20.08=7.10(1+r/1)^(1*12)}}}

{{{20.08=7.10(1+r)^(12)}}}

{{{ln(20.08)=ln(7.10)+ln(1+r)^(12)}}}

{{{ln(20.08)=ln(7.10)+(12)ln(1+r)}}}

{{{ln(20.08)-ln(7.10)=(12)ln(1+r)}}}

{{{1.039629511=(12)ln(1+r)}}}

{{{(1.039629511)/12=ln(1+r)}}}

{{{ 0.0866357926=ln(1+r)}}}

{{{e^0.0866357926=e^(ln(1+r))}}}

{{{1.090499439 = 1+r}}}

{{{0.090499439=r}}}

Now to double from P to 2P

{{{A=P(1+r/n)^(nt)}}}

{{{2P=P(1+0.090499439/1)^(1t)}}} 

{{{2cross(P)=cross(P)(1.090499439)^t}}}

{{{2=(1.090499439)^t}}}  

{{{ln(2)=ln(1.090499439)^t}}}

{{{ln(2)=t*ln(1.090499439)}}}

{{{ln(2)/ln(1.090499439)=t}}}

{{{8.000702283=t}}}

Answer: 8 years.

Edwin</pre>