document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=305012>Question 305012</A>: <I><SPAN STYLE=\"word-break: break-all;\"> I have five identical keys on a ring two of which will open the door what is the probability that i will get door open on the first or second try. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #219984 by </B><A HREF=/tutors/aboutme.mpl?userid=MathTherapy><B>MathTherapy(10552)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=MathTherapy><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=MathTherapy><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=219984\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> I have five identical keys on a ring two of which will open the door what is the probability that i will get door open on the first or second try.\r<BR>\n" );
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document.write( "The keys cannot be identical because if they are, anyone can close their eyes and any chosen key would open the door. It's apparent that they MAY appear identical.\r<BR>\n" );
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document.write( "In that case, using A and B as the correct keys, the probability of choosing A or B, or P(A or B) = P(A) + P(B)\r<BR>\n" );
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document.write( "Now this calculation is dependent on whether or not you return each key to the bunch after trying each one. If not, then we get:\r<BR>\n" );
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document.write( "P(A) + P(B) = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=2%2F5 ALIGN=MIDDLE  ALT=\"2%2F5\"   DISABLED_style= \"max-width:90%; height:auto;\" > + <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=1%2F4 ALIGN=MIDDLE  ALT=\"1%2F4\"   DISABLED_style= \"max-width:90%; height:auto;\" > = <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=highlight_green%2813%2F20%29 ALIGN=MIDDLE  ALT=\"highlight_green%2813%2F20%29\"   DISABLED_style= \"max-width:90%; height:auto;\" >\r<BR>\n" );
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