document.write( "Question 927549: Can someone help me with this question, please?\r
\n" ); document.write( "\n" ); document.write( "Sugar packaged by a certain machine has a mean weight of 5 lb and a standard deviation of 0.03 lb. For what values of c can the manufacturer of the machinery claim that the sugar packaged by this machine has a weight between 5 − c and 5 + c lb with probability at least 91%?
\n" ); document.write( "at least c =
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Algebra.Com's Answer #563065 by MathLover1(20850)\"\" \"About 
You can put this solution on YOUR website!
you are asked to find \"c\" such that, if \"W+\"denotes the weight of a package of sugar,\r
\n" ); document.write( "\n" ); document.write( "\"P%285-c+%3C+W+%3C5%2Bc+%29%3C=0.91\"
\n" ); document.write( "Since \"W\" is normally distributed, transform it into a *standard* normally distributed variable, \"Z\", using the formula:\r
\n" ); document.write( "\n" ); document.write( "Z=(W−μ)σ <=> W=Zσ+μ\r
\n" ); document.write( "\n" ); document.write( "where μ and σ are the mean and std. deviation of W's distribution.\r
\n" ); document.write( "\n" ); document.write( "\"P%285-c+%3C0.03Z%2B5+%3C5%2Bc%29+%3C=0.91\"\r
\n" ); document.write( "\n" ); document.write( "\"P%28-c%2A0.03%3CZ%3Cc%2A0.03%29%3C=0.91\"\r
\n" ); document.write( "\n" ); document.write( "\"P%28-c%2A0.03%3CZ%3Cc%2A0.03%29%3C=0.91\"\r
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\n" ); document.write( "\n" ); document.write( "Due to the symmetry of the normal curve, you can write this as\r
\n" ); document.write( "\n" ); document.write( "\"P%280%3CZ%3Cc%2A0.03%29%3C=0.455\"\r
\n" ); document.write( "\n" ); document.write( "\"P%28Z%3Cc%2A0.03%29-P%28Z%3C0%29%3C=0.455\"\r
\n" ); document.write( "\n" ); document.write( "\"P%28Z%3Cc%2A0.03%29-0.5%3C=0.455\"\r
\n" ); document.write( "\n" ); document.write( "\"P%28Z%3Cc%2A0.03%29%3C=0.955\"\r
\n" ); document.write( "\n" ); document.write( "Referring to a z-table, you get a corresponding z-value of \"1.70\"\r
\n" ); document.write( "\n" ); document.write( "In other words,\r
\n" ); document.write( "\n" ); document.write( "\"P%28Z%3Cc%2A0.03%29%3C=0.955\" <=> \"P%28Z%3C1.70%29%3C=0.955\"\r
\n" ); document.write( "\n" ); document.write( "which means \"1.7=c%2A0.03\" => \"c=0.051\"\r
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