document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=369802>Question 369802</A>: <I><SPAN STYLE=\"word-break: break-all;\"> concern 2-card hands from a standard 52-card deck..  A standard deck has13 cards from each of 4 suits (clubs, diamonds, hearts, spades).  The 13 cards have face value 2 through10, jack, queen, king, or ace.  Each face value is a \"kind\" of card.  The jack, queen, and king are \"face cards.\"<BR>\n" );
document.write( "20.  What is the probability that exactly one card is a spade?<BR>\n" );
document.write( "21.  What is the probability that at least one card is a spade?<BR>\n" );
document.write( "22.  What is the probability that both cards are face cards?<BR>\n" );
document.write( "23.  What is the probability that both cards are spade face cards?<BR>\n" );
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document.write( "a student takes a True/False quiz with 4 questions, each equally likely to be either T or F.  \r<BR>\n" );
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document.write( "50.  What is the probability of getting the first two questions correct?\r<BR>\n" );
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document.write( "52.  What is the probability of getting all four questions correct given that the answers to the first two questions are correct?<BR>\n" );
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document.write( "64. A directory on a computer's hard disk contains 12 files, 3 of which have viruses.  If a file with a virus is selected, the virus is detected and another file is then selected.  Find the expected number of files that must be selected before a virus-free file is found </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #263524 by </B><A HREF=/tutors/aboutme.mpl?userid=jrfrunner><B>jrfrunner(365)</B></A><img src=\"/images/stars/stars-10.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=jrfrunner><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=jrfrunner><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=263524\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> 20. What is the probability that exactly one card is a spade?<BR>\n" );
document.write( "P(Spade followed by NonSpade + Nonspade followed by Spade)=<BR>\n" );
document.write( "(13/52)*(39/51)+(39/52)*(13/51)<BR>\n" );
document.write( "21. What is the probability that at least one card is a spade?<BR>\n" );
document.write( "=1-P(both NonSpade) = 1-39/52*(38/51)<BR>\n" );
document.write( "22. What is the probability that both cards are face cards?<BR>\n" );
document.write( "P(face followed by face)=16/52*(15/51)<BR>\n" );
document.write( "23. What is the probability that both cards are spade face cards?<BR>\n" );
document.write( "=4/52*(3/51)<BR>\n" );
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document.write( "50. What is the probability of getting the first two questions correct? <BR>\n" );
document.write( "P(CC)=1/2*1/2=1/4<BR>\n" );
document.write( "52. What is the probability of getting all four questions correct given that the answers to the first two questions are correct?<BR>\n" );
document.write( "P(four correct/first two correct)=P(last two correct)=1/2*(1/2)=1/4\r<BR>\n" );
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