document.write( "Question 1031134: The tickets to a charity concert will sell out if the price is $15 per ticket. It is estimated that for each $1 increase in ticket's price, 20 tickets will remain unsold. What ticket price will maximize the charity's profit, if there are total 500 seats in the concert hall? \n" ); document.write( "
Algebra.Com's Answer #645862 by josmiceli(19441)\"\" \"About 
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With zero increase in ticket price, The
\n" ); document.write( "number of tickets sold is:
\n" ); document.write( "\"+n+=+500+\" and income is:
\n" ); document.write( "\"+15%2A500+=+7500+\"
\n" ); document.write( "--------------------
\n" ); document.write( "When there are \"+1%2An+\" dollar increases
\n" ); document.write( "in the ticket price, the income is:
\n" ); document.write( "\"+I+=+%28+15+%2B+n+%29%2A%28+500+-+20n+%29+\"
\n" ); document.write( "\"+I+=+7500+%2B+500n+-+300n+-+20n%5E2+\"
\n" ); document.write( "\"+I+=+-20n%5E2+%2B+200n+%2B+7500+\"
\n" ); document.write( "This function is a maximum when:
\n" ); document.write( "\"+n%5Bmax%5D+=+-b%2F%282a%29+\", where
\n" ); document.write( "\"+a+=+-20+\"
\n" ); document.write( "\"+b+=+200+\"
\n" ); document.write( "\"+n%5Bmax%5D+=+-200+%2F+%28+2%2A%28-20%29+%29+\"
\n" ); document.write( "\"+n%5Bmax%5D+=+5+\"
\n" ); document.write( "and
\n" ); document.write( "\"+I+=+-20%2A5%5E2+%2B+200%2A5+%2B+7500+\"
\n" ); document.write( "\"+I+=+-500+%2B+1000+%2B+7500+\"
\n" ); document.write( "\"+I+=+8000+\"
\n" ); document.write( "--------------------
\n" ); document.write( "With \"+n+=+5+\" $1 increases in ticket price,
\n" ); document.write( "the price that will maximize profit is:
\n" ); document.write( "\"+15+%2B+n+=+15+%2B+5+\"
\n" ); document.write( "\"+15+%2B+n+=+20+\"
\n" ); document.write( "$20
\n" ); document.write( "-------------
\n" ); document.write( "Here's the plot of income:
\n" ); document.write( "\"+graph%28+400%2C+400%2C+-10%2C+30%2C+-1000%2C+9000%2C+-20x%5E2+%2B+200x+%2B+7500+%29+\"
\n" ); document.write( "
\n" );