document.write( "Question 107556: In planning for a new item, a manufacturer assumes that the number of items produced x and the cost in dollars C of producing these items are related by a linear equation. Projections are that 100 items will cost $10,000 to produce and that 300 items will cost $22,000 to produce. Find the equation that relates C and x. \n" ); document.write( "
Algebra.Com's Answer #78331 by josmiceli(19441)\"\" \"About 
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The equation is linear, so it will have the form \"C+=+ax+%2B+b\"
\n" ); document.write( "Cis plotted on the vertical axis, because it is the
\n" ); document.write( "\"dependant\" variable (dependant on x items produced)
\n" ); document.write( "x is the independant variable plotted on the horizontal axis.
\n" ); document.write( "b is the \"C intercept\". It's the cost of producing zero items
\n" ); document.write( "(overhead). From the points P2(x2,C2) and P1(x1,C1)
\n" ); document.write( " I can determine the slope, a
\n" ); document.write( "\"a+=+%28C%5B2%5D+-+C%5B1%5D%29+%2F+%28x%5B2%5D+-+x%5B1%5D%29\"
\n" ); document.write( "where
\n" ); document.write( "\"C%5B2%5D+=+22000\"
\n" ); document.write( "\"C%5B1%5D+=+10000\"
\n" ); document.write( "\"x%5B2%5D+=+300\"
\n" ); document.write( "\"x%5B1%5D+=+100\"
\n" ); document.write( "\"a+=+%2822000+-+10000%29+%2F+%28300+-+100%29\"
\n" ); document.write( "\"a+=+12000+%2F+200\"
\n" ); document.write( "\"a+=+60\"
\n" ); document.write( "Now I have \"C+=+60x+%2B+b\"
\n" ); document.write( "I'll pick one of the points P(x,C) to solve for b
\n" ); document.write( "\"10000+=+60%2A100+%2B+b\"
\n" ); document.write( "\"b+=+10000+-+6000\"
\n" ); document.write( "\"b+=+4000\"
\n" ); document.write( "\"C+=+60x+%2B+4000\" answer
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