document.write( "Question 1121250: 1000 light bulbs with a main life of 120 days are installed.
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Algebra.Com's Answer #737055 by ikleyn(52781)\"\" \"About 
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\n" ); document.write( "1000 light bulbs with a \"highlight%28cross%28main%29%29\" mean life of 120 days are installed.
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\n" ); document.write( "\n" ); document.write( "            First of all,  pay attention on how I edited your post.\r
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\n" ); document.write( "\n" ); document.write( "From the first glance,  it is clear that the given info/input is NOT SUFFICIENT to solve the problem - appropriate
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\n" ); document.write( "\n" ); document.write( "Moreover,  making appropriate and likelihood assumptions is the  PART of the solution.\r
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document.write( "I will assume that this part of the condition   \"mean life of 120 days\"  can be interpreted as \"all 1000 light bulbs will expire in 240 days\".\r\n" );
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document.write( "It is first assumption. The second assumption is that the life time is distributed uniformly during this period of 240 days.\r\n" );
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document.write( "    Notice that the second assumption is consistent with the first one (!)\r\n" );
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document.write( "If so, then the proportion works\r\n" );
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document.write( "\"x%2F90\" = \"1000%2F240\",\r\n" );
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document.write( "which gives  x = \"%2890%2A1000%29%2F240\" = 375.\r\n" );
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\n" ); document.write( "\n" ); document.write( "Answer.   Under the proposed / accepted assumptions,  375 light bulbs will expire in  90  days.\r
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