document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=376017>Question 376017</A>: <I><SPAN STYLE=\"word-break: break-all;\"> USA Today reports that about 25% of all prison parolees become repeat offenders. Alice is a social worker whose job is to counsel people on parole. Let us say success means a person does not become a repeat offender. Alice has been given a group of four parolees.\r<BR>\n" );
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document.write( "(a) Find the probability P(r) of r successes ranging from 0 to 4.\r<BR>\n" );
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document.write( "(b) What is the expected number of parolees in Alice's group who will not be repeat offenders? What is the standard deviation? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #267449 by </B><A HREF=/tutors/aboutme.mpl?userid=edjones><B>edjones(8007)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=edjones><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=edjones><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=267449\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> let x=.75 and y=.25<BR>\n" );
document.write( "(x+y)^4 Binomial distribution.<BR>\n" );
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document.write( "a)<BR>\n" );
document.write( "x^4=.3164 P(4)<BR>\n" );
document.write( "4x^3y=.4219<BR>\n" );
document.write( "6x^2y^2=.2109<BR>\n" );
document.write( "4xy^3=.0469<BR>\n" );
document.write( "y^4=.0039 P(0)<BR>\n" );
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document.write( "b)<BR>\n" );
document.write( "mean=n*p=4*.75=3 the expected number of parolees in Alice's group who will not be repeat offenders.<BR>\n" );
document.write( "Standard deviation=sqrt(np(1-p))<BR>\n" );
document.write( "=sqrt(4*.75*.25)<BR>\n" );
document.write( "=sqrt(.75)<BR>\n" );
document.write( "=0.8660<BR>\n" );
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document.write( "Ed </SPAN>\n" );
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