Question 1019767
Let {{{ h }}} = the initial height of the candle
I can say:
[ final height ] = [ rate of decrease]*[ time ] + [ initial height ]
{{{ h = -.5*h + h[0] }}}
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Convert minutes to hrs
{{{ 5/60 = 1/12 }}} hrs
[ .5 in/hr ] x [ hrs ] = [ inches ]
{{{ (1/2)*(1/12) = 1/24 }}} height decrease after 5 min 
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{{{ h[0] = 3.5 + 1/24 }}}
{{{ h[0] = 3.5 + .04167 }}}
{{{ h[0] = 3.54167 }}}
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{{{ h = -.5t + 3.54167 }}}
This should give the height after {{{ t }}} min
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check:
{{{ t = 1/12 }}}
{{{ h = -1/24 + 3.54167 }}}
{{{ h = -.041667 + 3.54167 }}}
{{{ h = 3.5 }}}
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Here's the plot:
Hope I got it
{{{ graph( 400,400, -5, 12, -5, 7, -.5x + 3.54167 ) }}}