document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=258784>Question 258784</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Amniocentesis tests result in miscarriage 0.5% of the time. Assuming each test is independent and follows a Bernoulli random variable, then what is the variance of one test? What is the variance of 400 tests? I found the equation for variance p(1-p), but it doesn't take into account the number of tests. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #190509 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=190509\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Amniocentesis tests result in miscarriage 0.5% of the time. Assuming each test is independent and follows a Bernoulli random variable, then what is the variance of one test? What is the variance of 400 tests? I found the equation for variance p(1-p), but it doesn't take into account the number of tests.<BR>\n" );
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document.write( "For a binomial distribution variance = npq<BR>\n" );
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document.write( "Your problem:<BR>\n" );
document.write( "variance = 400*0.05*0.95 = 19<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
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