document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=438069>Question 438069</A>: <I><SPAN STYLE=\"word-break: break-all;\"> in a survey , 65% of Americans said they own an answering machine. If 20 Americans are selected randomly a) find the probabilities that at least 18 people own an answering machine and b) find the mean and the standard deviation the number of people owning an answering machine . </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #303032 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=303032\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\">  in a survey , 65% of Americans said they own an answering machine. <BR>\n" );
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document.write( "If 20 Americans are selected randomly <BR>\n" );
document.write( "a) find the probabilities that at least 18 people own an answering machine<BR>\n" );
document.write( "P(18<= x <=20) = 1-binomcdf(20,0.65,17) = 0.0121<BR>\n" );
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document.write( "b) find the mean and the standard deviation the number of people owning an answering machine .<BR>\n" );
document.write( "mean = np = 20*0.65 = 13<BR>\n" );
document.write( "std = sqrt(13*0.35) = 2.1331<BR>\n" );
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document.write( "cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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document.write( " </SPAN>\n" );
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