document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1108906>Question 1108906</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Scores on a certain test are normally distributed with a variance of 22. A researcher wishes to estimate the mean score achieved by all adults on the test. \r<BR>\n" );
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document.write( "Find the sample size needed to assure with 95% confidence that the sample mean will not differ from the population mean by more than 2 units. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #723937 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=723937\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Scores on a certain test are normally distributed with a variance of 22. A researcher wishes to estimate the mean score achieved by all adults on the test. <BR>\n" );
document.write( "Find the sample size needed to assure with 95% confidence that the sample mean will not differ from the population mean by more than 2 units. <BR>\n" );
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document.write( "Since ME = z*s/sqrt(n), n = [z*s/ME]^2<BR>\n" );
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document.write( "Ans: n = [1.96*22/2]^2 = 21.56 ~ 22 when rounded up<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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