document.write( "Question 1196438: On a highway a wreck occurred and caused a 12 mile traffic
\n" ); document.write( "jam on one side of the road. The average car is 13.5 feet in
\n" ); document.write( "length, the average truck is 20 feet in length, and the
\n" ); document.write( "average 18 wheeler tractor trailer is 75 feet in length. 65%
\n" ); document.write( "of the traffic jam consists of cars, 20% trucks, and 15% 18
\n" ); document.write( "wheeler tractor trailers. The average distance between
\n" ); document.write( "vehicles is 2.5 feet. How many cars are in the traffic jam ? \n" ); document.write( "

Algebra.Com's Answer #829266 by ikleyn(52915) $\"\"$ $\"About$

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\n" ); document.write( "On a highway a wreck occurred and caused a 12 mile traffic
\n" ); document.write( "jam on one side of the road. The average car is 13.5 feet in
\n" ); document.write( "length, the average truck is 20 feet in length, and the
\n" ); document.write( "average 18 wheeler tractor trailer is 75 feet in length. 65%
\n" ); document.write( "of the traffic jam consists of cars, 20% trucks, and 15% 18
\n" ); document.write( "wheeler tractor trailers. The average distance between
\n" ); document.write( "vehicles is 2.5 feet. How many cars are in the traffic jam ?
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document.write( "Let x be the number of cars in the jam (the unknown value under the problem's question).\r\n" );
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document.write( "Then the total length of the jam, from the first bumper to the last bumper, is\r\n" );
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document.write( "    0.65*x*13.5 + 0.20*x*20 + 0.15*x*75 + (x-1)*2.5  feet.\r\n" );
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document.write( "It is exactly 12 miles, or 12*5280 = 63360 feet.\r\n" );
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document.write( "So, you have this equation\r\n" );
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document.write( "    0.65*x*13.5 + 0.20*x*20 + 0.15*x*75 + (x-1)*2.5 = 63360,\r\n" );
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document.write( "or\r\n" );
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document.write( "    24.025x + 2.5x - 2.5 = 63360\r\n" );
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document.write( "    26.525x              = 63360 + 2.5 = 63362.5\r\n" );
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document.write( "          x                            = 63362.5/26.525 = 2388.784 before rounding and 2489 after rounding.\r\n" );
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document.write( "ANSWER.  2489 vehicles, in total;  of them,  0.65*2489 = 1553 (rounded) are cars.\r\n" );
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