document.write( "Question 153600: The elevator in the Washington Monument takes 75 seconds to travel 500 feet to the top floor. What is the speed of the elevator in miles per hour? Give your answer to two significant digits. \n" ); document.write( "
Algebra.Com's Answer #113066 by Edwin McCravy(20056)\"\" \"About 
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Edwin's solution:\r
\n" ); document.write( "\n" ); document.write( "The elevator in the Washington Monument takes 75 seconds to travel 500 feet to the top floor. What is the speed of the elevator in miles per hour? Give your answer to two significant digits.
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document.write( "\"%28500ft%29%2F%2875s%29\"\r\n" );
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document.write( "Now use the fact that \"5280ft=1mi\" to create\r\n" );
document.write( "a unit fraction to cancel away the \"ft\"'s.  Since\r\n" );
document.write( "\"ft\" is in the top, we want to create a unit \r\n" );
document.write( "fraction with \"ft\" on the bottom, so we create\r\n" );
document.write( "the unit fraction \"1mi%2F%285280ft%29\". So we multiply\r\n" );
document.write( "by that fraction:\r\n" );
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document.write( "\"%28500ft%29%2F%2875s%29\"x\"1mi%2F%285280ft%29\".\r\n" );
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document.write( "and then cancel away the \"ft\"'s.\r\n" );
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document.write( "\"%28500cross%28ft%29%29%2F%2875s%29\"x\"1mi%2F%285280cross%28ft%29%29\"\r\n" );
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document.write( "Now use the fact that \"60s=1min\" to create\r\n" );
document.write( "a unit fraction to cancel away the \"s\"'s.  Since\r\n" );
document.write( "\"s\" is in the bottom, we want to create a unit \r\n" );
document.write( "fraction with \"s\" on the top, so we create\r\n" );
document.write( "the unit fraction \"60s%2F%281min%29\". So we multiply\r\n" );
document.write( "by that fraction:\r\n" );
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document.write( "\"%28500cross%28ft%29%29%2F%2875s%29\"x\"1mi%2F%285280cross%28ft%29%29\"x\"60s%2F%281min%29\".\r\n" );
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document.write( "and then cancel away the \"s\"'s.\r\n" );
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document.write( "\"%28500cross%28ft%29%29%2F%2875cross%28s%29%29\"x\"1mi%2F%285280cross%28ft%29%29\"x\"60cross%28s%29%2F%281min%29\". \r\n" );
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document.write( "Now use the fact that \"60min=1h\" to create\r\n" );
document.write( "a unit fraction to cancel away the \"min\"'s.  Since\r\n" );
document.write( "\"min\" is in the bottom, we want to create a unit \r\n" );
document.write( "fraction with \"min\" on the top, so we create\r\n" );
document.write( "the unit fraction \"60min%2F%281h%29\". So we multiply\r\n" );
document.write( "by that fraction:\r\n" );
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document.write( "\"%28500cross%28ft%29%29%2F%2875cross%28s%29%29\"x\"1mi%2F%285280cross%28ft%29%29\"x\"60cross%28s%29%2F%281min%29\"x\"60min%2F%281h%29\".  \r\n" );
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document.write( "and then cancel away the \"min\"'s.\r\n" );
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document.write( "\"%28500cross%28ft%29%29%2F%2875cross%28s%29%29\"x\"1mi%2F%285280cross%28ft%29%29\"x\"60cross%28s%29%2F%281cross%28min%29%29\"x\"60cross%28min%29%2F%281h%29\". \r\n" );
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document.write( "Now the only units that are not canceled away are \"mi\" \r\n" );
document.write( "on the top and the \"h\" on the bottom.\r\n" );
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document.write( "\"%28%28500%29%2860%29%2860%29mi%29%2F%2875%29%285280%29h\"\r\n" );
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document.write( "\"1800000mi%2F%28396000h%29\"\r\n" );
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document.write( "\"4.545454545\"\"mi%2Fhr\"\r\n" );
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document.write( "Rounding to two significant digits:\r\n" );
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document.write( "\"4.6\"\"mi%2Fhr\"\r\n" );
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document.write( "Edwin
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