document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1186284>Question 1186284</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The random variable X has the probability distribution shown at right<BR>\n" );
document.write( "Find the standard deviation of X\r<BR>\n" );
document.write( "\n" );
document.write( "x    │ P(X=x)<BR>\n" );
document.write( "1    │ 0.45<BR>\n" );
document.write( "3   │0.10<BR>\n" );
document.write( "5   │ 0.45 </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #817173 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=817173\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> E(X)=mean = x*p(x) all summed<BR>\n" );
document.write( "this is 0.45+0.30+2.25, multiplying the 3 rows. They add to 3, the mean, which can be seen also by the symmetry of the distribution.<BR>\n" );
document.write( "sd is sqrt sum of  (square differences)(probability)/n<BR>\n" );
document.write( "=4*0.45+0*0.10+4*0.45<BR>\n" );
document.write( "=3.60<BR>\n" );
document.write( "sqrt (3.60)=1.90<BR>\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );