document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1113090>Question 1113090</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Gestation periods of humans are normally distributed with a mean of 266 days and a standard deviation of 16 days?\r<BR>\n" );
document.write( "\n" );
document.write( "1. Find the probability that a random sample of 36 pregnancies has a mean gestation period within 5 days of the mean. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #728150 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=728150\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\">  Gestation periods of humans are normally distributed with a mean of 266 days and a standard deviation of 16 days? <BR>\n" );
document.write( "1. Find the probability that a random sample of 36 pregnancies has a mean gestation period within 5 days of the mean. <BR>\n" );
document.write( "-----<BR>\n" );
document.write( "std of the sample means = 16/sqrt(36) = 16/6 = 8/3<BR>\n" );
document.write( "--------<BR>\n" );
document.write( "z(261) = (261-266)/(8/3) = -5/(8/3) = -1.875<BR>\n" );
document.write( "z(271) = +5/(8/3) = +1.875<BR>\n" );
document.write( "-----<BR>\n" );
document.write( "p(261< x-bar <271) = P(-1.875< z <+1.875) = normalcdf(-1.875,1.875) = 0.94<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
document.write( "------------ </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );