Question 887917
{{{0.20X=X(1/2)^(T/5730)}}}
{{{0.20=(1/2)^(T/5730)}}}
{{{log(1/2,(0.2))=T/5730}}}
{{{T/5730=(log((0.2))/log((0.5)))}}}
{{{T=5730*(log((0.2))/log((0.5)))}}}
{{{T=5730*2.322}}}
{{{T=13305}}}{{{years}}}