document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=322202>Question 322202</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The standard deviation of a variable is 15. if a sample of 100 individuals is selected, compute the standard error of the mean. What size sample is necessary to double the standard error of the mean? \r<BR>\n" );
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document.write( "I got the answer to that question. It is n=25.\r<BR>\n" );
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document.write( "This is the question I need help with...\r<BR>\n" );
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document.write( "What size sample is needed to cut the standard error of the mean in half?\r<BR>\n" );
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document.write( "Hope you can help, Thank you! :) </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #230667 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=230667\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The standard deviation of a variable is 15. <BR>\n" );
document.write( "if a sample of 100 individuals is selected, compute the standard error of the mean. <BR>\n" );
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document.write( "standard error = 15/sqrt(100) = 1.5<BR>\n" );
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document.write( "What size sample is necessary to double the standard error of the mean?<BR>\n" );
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document.write( "Solve: 10/sqrt(n) = 2*1.5<BR>\n" );
document.write( "10/sqrt(n) = 3<BR>\n" );
document.write( "sqrt(n) = 10/3<BR>\n" );
document.write( "n = (10/3)^2<BR>\n" );
document.write( "n = 100/9 = 11.11<BR>\n" );
document.write( "Round up to n = 12<BR>\n" );
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document.write( "What size sample is needed to cut the standard error of the mean in half?<BR>\n" );
document.write( "Solve 10/sqrt(n) = 3/4<BR>\n" );
document.write( "sqrt(n) = 10/(3/4)<BR>\n" );
document.write( "sqrt(n) = 40/3 <BR>\n" );
document.write( "n = (40/3)^2 <BR>\n" );
document.write( "n = 178 when rounded<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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