document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1161656>Question 1161656</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The lengths of pregnancies are normally distributed with a mean of 264 days and a standard deviation of 21 days. If 100 women are randomly selected, find the probability that they have a mean pregnancy between 263 days and 265 days. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #787290 by </B><A HREF=/tutors/aboutme.mpl?userid=Boreal><B>Boreal(15235)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Boreal><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=Boreal><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=787290\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Since it is symmetric, can get 1 probability and double it.\r<BR>\n" );
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document.write( "z=(x-mean)/sd/sqrt(n)<BR>\n" );
document.write( "=-1*10/21, inverting the denominator and multiplying. <BR>\n" );
document.write( "=-10/21 or 0.476\r<BR>\n" );
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document.write( "want the probability of z between -.476 and +.476 which is 0.3659 </SPAN>\n" );
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