document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1186190>Question 1186190</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The amounts of electricity bills for all households in a particular city have an <BR>\n" );
document.write( "approximately normal distribution with a mean of $140 and a standard deviation of <BR>\n" );
document.write( "$30. Find the probability that the mean amount of electricity bills for a random sample <BR>\n" );
document.write( "of 75 households selected from this city will be between $132 and $136. My email address is www.cosmashiltoon@gmail.com<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #817214 by </B><A HREF=/tutors/aboutme.mpl?userid=Theo><B>Theo(13342)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Theo><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/cgi-bin/show-face.mpl?user=Theo><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=817214\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> population mean = 140.<BR>\n" );
document.write( "population standard deviation = 30<BR>\n" );
document.write( "sample size = 75\r<BR>\n" );
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document.write( "when you are dealing with the mean of a sample, you need to use the standard error.\r<BR>\n" );
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document.write( "standard error = standard deviation divided by square root of smaple size = 30 / sqrt(75) = 3.4641 rounded to 4 decimal places.\r<BR>\n" );
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document.write( "probability that the sample mean will be between 132 and 136 is is equal to .1136 = 11.36%.\r<BR>\n" );
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document.write( "calculator used can be found at <a  rel=nofollow HREF= \"https://davidmlane.com/hyperstat/z_table.html\" target = \"_blank\">https://davidmlane.com/hyperstat/z_table.html</a>\r<BR>\n" );
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document.write( "here's a display of the results from using that calculator.\r<BR>\n" );
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