document.write( "Question 715363: Could you please help me with this word problem?\r
\n" ); document.write( "\n" ); document.write( "Problem: In 1927, Charles Lindbergh was the first person to fly nonstop across the Atlantic Ocean. Today, commercial airliners fly from New York to Paris five times as fast, or 400 miles/hour faster than Lindbergh's plane.\r
\n" ); document.write( "\n" ); document.write( "a. At what speed did Charles Lindbergh's plane fly?\r
\n" ); document.write( "\n" ); document.write( "b. At what speed do commercial airplanes fly today?\r
\n" ); document.write( "\n" ); document.write( "c. If it took Lindbergh about 36 hours to cross the Atlantic, what distance did he fly?\r
\n" ); document.write( "\n" ); document.write( "d. How long does it take a commercial airplane today to fly across the Atlantic?\r
\n" ); document.write( "\n" ); document.write( "(For section a i thought the answer might be 80 mph. I got this by trying out the equation 400/5=80... However, i feel this is incorrect.) \n" ); document.write( "

Algebra.Com's Answer #439399 by Edwin McCravy(20056) $\"\"$ $\"About$

You can put this solution on YOUR website!
a. At what speed did Charles Lindbergh's plane fly?
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document.write( "Let the answer be x mph.\r\n" );
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\n" ); document.write( "Today, commercial airliners fly from New York to Paris five times as fast,
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document.write( "Therefore commercial airliners fly 5x mph\r\n" );
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\n" ); document.write( "or 400 miles/hour faster than Lindbergh's plane.
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document.write( "Therefore commercial airliners also fly x+400 mph.\r\n" );
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document.write( "So 5x mph must equal x+400 mph, so\r\n" );
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document.write( "           5x = x + 400\r\n" );
document.write( "           4x = 400\r\n" );
document.write( "            x = 100\r\n" );
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document.write( "So Lindberg flew at 100 mph. \r\n" );
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\n" ); document.write( "b. At what speed do commercial airplanes fly today?
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document.write( "5 times as fast as Lindberg, or 5×100 or 500 mph. Or you can say \r\n" );
document.write( "400 mph faster then 100 mph or 500 mph.  Either way you get 500 mph. \r\n" );
document.write( "

\n" ); document.write( "c. If it took Lindbergh about 36 hours to cross the Atlantic, what
\n" ); document.write( "distance did he fly?
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document.write( "Distance = Speed × time = 100×36 = 3600 miles\r\n" );
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\n" ); document.write( "d. How long does it take a commercial airplane today to fly across
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document.write( "TIME = DISTANCE÷SPEED = 3600÷500 = 7.2 hours = 7 hours 12 minutes\r\n" );
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document.write( "You can also get that answer by taking th of 36 hours,\r\n" );
document.write( "because going 5 times as fast will take only th of the 36\r\n" );
document.write( "hours that Lindberg took, and th of 36 is also 7.2 hours,\r\n" );
document.write( "or 7 hours 12 minutes.\r\n" );
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document.write( "Edwin

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