Question 644067
The general form of the equation is
{{{ C = m*d + b }}} where {{{ m }}} is the slope
Plot {{{ C }}} on the vertical axis
Plot {{{ d }}} on the horizontal
Slope is ( change in C ) / ( change in d )
{{{ ( 470 - 350 ) / ( 900 - 420 ) }}}
{{{ 120 / 480 = 1/4 }}}
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{{{ m = 1/4 }}}
Now just plug in one of the 2 given points
to find {{{ b }}}, the intercept on the vertical axis
{{{ 470 = (1/4)*900 + b }}}
{{{ b = 470 - 225 }}}
{{{ b = 245 }}}
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The equation is {{{ C = (1/4)*d + 245 }}}
check answer:
{{{ 350 = (1/4)*420 + 245 }}}
{{{ 350 = 105 + 245 }}}
{{{ 350 = 350 }}}
Here's the plot:
{{{ graph( 400, 400, -100, 1000, -100, 500, (1/4)*x + 245 ) }}}