document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=33051>Question 33051</A>: <I><SPAN STYLE=\"word-break: break-all;\"> I've tried working this but i'm pretty sure I am really wrong!  \r<BR>\n" );
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document.write( "A drug company had previously reported that 1% of patients have a negative reaction to drug X.  After the drug hits the market concerns are raised that the actual probability of a negative reaction is higher than the drug company reported.  In an investegatory trial 500 patients are given the drug and 9 have a negative reaction.  \r<BR>\n" );
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document.write( "a) what would be the expected number of negative reactions in the study of 500 patients given the drug company's rate is correct? .01* 500=5\r<BR>\n" );
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document.write( "b) What would be the variance of negative reactions in this study of 500 patients given that the drug company's rate is correct?  I have no idea!\r<BR>\n" );
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document.write( "c) How likely would observing 9 negative reactions in 500 patients have been given the drug company's intial claim was correct.  I'm not sure how to type in what I did but i'll try (500!/9!)*.01^9*.99^491.  my answer is .035 which means very unlikely.  \r<BR>\n" );
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document.write( "d) How likely would observing 1 negative reaction in 500 patients have been given the drug company's initial claim was correct?  I did the same sort of thing (500!/1!)*.01^1*.99^499=.033.\r<BR>\n" );
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document.write( "e) How likely would it be to observe 9 or more negative reactions.  The answer is the same as part c.\r<BR>\n" );
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document.write( "Any help is greatly appreciated! </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #19483 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=19483\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> a. np=500(0.01)=5<BR>\n" );
document.write( "b) It's binomial. The standard deviation is sqrt(npq)<BR>\n" );
document.write( "   = sqrt(500.01(0.9)=0.671<BR>\n" );
document.write( "c) I get 0.036. , but it's 500!/[491!*9!](0.01)^9(0.9)^491 or binompdf(500,0.01,9)<BR>\n" );
document.write( "d)  I get 0.33 also; it's 500!/[499!*1!](0.01)(0.99)^499<BR>\n" );
document.write( "e) I get 0.067 or [1 - binomcdf(500,0.01,8)]<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
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