document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1190746>Question 1190746</A>: <I><SPAN STYLE=\"word-break: break-all;\"> According to tables provided by the National Center for Health Statistics in Vital Statistics of the <BR>\n" );
document.write( "United States, there is roughly an 80% chance that a person of age 20 years will be alive at age 65 <BR>\n" );
document.write( "years. Suppose that three people of age 20 years are selected at random. Find the probability that <BR>\n" );
document.write( "the number alive at age 65 years will be<BR>\n" );
document.write( "A. exactly two.<BR>\n" );
document.write( "B. at most one.<BR>\n" );
document.write( "C. at least one.<BR>\n" );
document.write( "D. Determine the probability distribution of the number alive at age 65. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #822532 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=822532\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> for 0 alive is 0.2^3=0.008<BR>\n" );
document.write( "for 1 alive is 3*0.2^2*0.8=0.096<BR>\n" );
document.write( "for 2 alive is 3*0.2*0.8^2=0.384<BR>\n" );
document.write( "for all 3 it is 0.8^3=0.512<BR>\n" );
document.write( "they add to 1, as they should.\r<BR>\n" );
document.write( "\n" );
document.write( "answers<BR>\n" );
document.write( "a. 0.384<BR>\n" );
document.write( "b. is 0 or 1 with prob. 0.104<BR>\n" );
document.write( "c. at least 1 is 1- p(0)=0.992<BR>\n" );
document.write( "d. The probability distribution is above.<BR>\n" );
document.write( "Sometimes it is just easier to write down the whole probability distribution and then answer the questions, when there are several questions. When n is small and the decimals are straightforward, it almost always is easier.  </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );