Question 956464
{{{ A = P*( 1 + r/n )^(n*t) }}}
{{{ n = 2 }}}
{{{ r = .05 }}}
{{{ P = 775 }}}
{{{ A = 2*775 }}}
----------------
{{{ 1550 = 775*(  1 + .05/2 )^( 2t ) }}}
{{{ 2 = ( 1 + .025 )^( 2t ) }}}
{{{ 1.025^(2t) = 2 }}}
Take the log of both sides
{{{ 2t*log( 1.025 ) = log(2) }}}
{{{ 2t*.010724 = .30103 }}}
{{{ t = .30103 / .021448 }}}
{{{ t = 14.0353 }}}
--------------
In 14 yrs, $775 will double
{{{ 2 = ( 1 + .025 )^( 2t ) }}}
{{{ 2 = 1.025^( 2t ) }}}
{{{ 2 = 1.025^( 2*14.0353 ) }}}
{{{ 2 = 1.025^28.0706 }}}
{{{ 2 = 1.99998 }}}
close enough