Question 1046800
{{{ A = P*( 1 + r/n )^(n*t) }}}
Let {{{ I }}} = the interest earned
given:
{{{ P = 5600 }}}
{{{ t = 3 }}}
{{{ I = 1200 }}}
{{{ n = 1 }}} ( I'm assuming this )
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The interest earned, {{{ I }}} is:
{{{ I = P*( 1 + r/n )^(n*t) - P }}}
{{{ 1200 = 5600*( 1 + r/1 )^( 1*3 ) - 5600 }}}
{{{ 1200 = 5600*( 1 + r )^3 - 5600 }}}
{{{ 1200/5600 = ( 1 + r )^3 - 1 }}}
{{{ 3/14 = ( 1 + r )^3 - 1 }}}
{{{ 17/14 = ( 1 + r )^3 }}}
Take the log base 10 of both sides
{{{ log( 17 ) - log( 14 ) = 3*log(( 1 + r )) }}}
{{{ 1.23045 - 1.14613 = 3*log(( 1 + r )) }}}
{{{ 3*log(( 1 + r )) = .084322 }}}
{{{ log(( 1 + r )) = .028107 }}}
{{{ 1 + r = 10^.028107 }}}
{{{ 1 + r = 1.06686 }}}
{{{ r = .06686 }}}
the annual interest rate is 6.69%
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check my math & get a 2nd opinion