document.write( "Question 627275: Please help with this I am struggling,\r
\n" ); document.write( "\n" ); document.write( "Research shows the average cell phone will be 26 months before repairs are needed. If the standard deviation for the data is 6 months, what length of time should be set for a warranty such that less than 10% of all phones will need repairs during the warranty period.\r
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Algebra.Com's Answer #394812 by ewatrrr(24785) $\"\"$ $\"About$

You can put this solution on YOUR website!

 
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document.write( "Hi, Re TY, Yes at less than 26 months... 50% would would be defective... 
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document.write( "average cell phone will be 26 months before repairs are needed. If the standard deviation for the data is 6 months
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document.write( " z = (x - 26)/6
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document.write( "what length of time should be set for a warranty such that less than 10% of all phones will need repairs during the warranty period.
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document.write( "  = (x-26)/6      | Note: Excel NORMSINV(0.1)= -1.2816
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document.write( " = x 
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