document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=962269>Question 962269</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The diameter of a brand of Ping Pong balls is approximately normally distributed, with a mean of 1.31 inches and a standard deviation of 0.08 inches. A random sample of 4 balls is selected. \r<BR>\n" );
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document.write( "-The probability is 50% that the sample mean will be between what two values, symmetrically distributed around the population mean?\r<BR>\n" );
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document.write( "Lower bound: __ inches<BR>\n" );
document.write( "Upper bound: __ inches\r<BR>\n" );
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document.write( "I'm pretty sure I need to start by finding a Z score, but am having a hard time figuring which formulas I need to use, for that and to finish the problem. Thanks. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #587860 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=587860\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The diameter of a brand of Ping Pong balls is approximately normally distributed, with a mean of 1.31 inches and a standard deviation of 0.08 inches. A random sample of 4 balls is selected.<BR>\n" );
document.write( " -The probability is 50% that the sample mean will be between what two values, symmetrically distributed around the population mean?<BR>\n" );
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document.write( "Looks like you want a 50% confidence interval.<BR>\n" );
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document.write( "sample mean = x-bar = 1.31<BR>\n" );
document.write( "Margin of Error = ME = z*s/sqrt(n))= 0.6745*0.08/sqrt(4) = 0.0270<BR>\n" );
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document.write( "50%CI:: 1.31-0.0270 < u < 1.31+0.0270<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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document.write( " Lower bound: 1.2831 inches<BR>\n" );
document.write( " Upper bound: 1.3369 inches <BR>\n" );
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