document.write( "Question 158245: I got the question incorrect, but I do not know what I did wrong.\r
\n" ); document.write( "\n" ); document.write( "The cost of manufacturing notebooks varies inversely as the number of notebooks. If it costs 50 cents a notebook when 10,000 are manufactured, how much will it cost if 18,000 are made?\r
\n" ); document.write( "\n" ); document.write( "MY WORK:
\n" ); document.write( "50/10,000=x/18,000\r
\n" ); document.write( "\n" ); document.write( "1/200=x/18,000 \r
\n" ); document.write( "\n" ); document.write( "200x=18,000
\n" ); document.write( "x=90 cents \n" ); document.write( "

Algebra.Com's Answer #116617 by ilana(307) $\"\"$ $\"About$

You can put this solution on YOUR website!
It says the cost varies inversely with the number of notebooks. That means that as the number of books increases, the cost per book decreases. That's your first clue that your answer is wrong. You set up a direct proportion, y=kx, rather than an inverse proportion, y=k/x. Since the cost is $.50 per book for 10,000 books, you can write the equation .50 = k/10000, so k = 5000. That means the inverse function is y = 5000/x. Now substitute 18000 for x to get y = 5000/18000 = 0.27777. So it costs 28 cents per notebook when 18,000 are manufactured. \n" ); document.write( "

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