Question 767705
Growth model:

{{{
4P[0] =P[0](1+0.025)^t
}}}

which we simplify to get


{{{
4 =(1+0.025)^t
}}}

solving for t ...

{{{ln(4)=t*ln(1.025)
}}}



{{{ln(4)/ln(1.025)=t
}}}

this is about 81 years