document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1089233>Question 1089233</A>: <I><SPAN STYLE=\"word-break: break-all;\"> a coin is tossed 9 times what is the probability of getting ?<BR>\n" );
document.write( "a)five heads<BR>\n" );
document.write( "b)at least two heads </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #703578 by </B><A HREF=/tutors/aboutme.mpl?userid=rothauserc><B>rothauserc(4718)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=rothauserc><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=rothauserc><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=703578\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> We use the binomial probability formula,<BR>\n" );
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document.write( "Probability (P) ( k successes in n trials ) = nCk * p^k * (1-p)^(n-k)<BR>\n" );
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document.write( "Note that nCk = n! / (k! * (n-k)!), p = 0.5<BR>\n" );
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document.write( "a) P ( k=5, n=9) = 9C5 * 0.5^5 * (1-0.5)^(9-5) = 0.246 approx 0.25<BR>\n" );
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document.write( "b) P ( at least 2 heads ) = 1 - P ( k=0, n=9) - P (k=1, n=9) = 1 - 0.002 - 0.020 = 0.978 approx 0.98<BR>\n" );
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