Question 872560
The formula is:
{{{ S = 500*( 1 + .1 )^n }}}
{{{ S }}} = Salary
{{{ n }}} = number of the month, starting 
with month {{{ 0 }}}
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During 1st month:
{{{ S = 500*( 1 + .1 )^0 }}}
{{{ S = 500 }}}
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During 4th month:
{{{ S = 500*( 1 + .1 )^3 }}}
{{{ S = 500*1.331 }}}
{{{ S = 665.5 }}}
During the 4th month the
person earns $665.50