document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1068243>Question 1068243</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Steele Electronics Inc. sells expensive brands of stereo equipment in several shopping malls. The marketing research department of Steele reports that 33% of the customers entering the store that indicate they are browsing will, in the end, make a purchase. Let the last 24 customers who enter the store be a sample.\r<BR>\n" );
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document.write( "What is the probability 13 or more make a purchase? (Round the final answer to 4 decimal places.)<BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #683549 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=683549\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Can use the normal approximation to the binomial and compare with the exact number using the binomial distribution.<BR>\n" );
document.write( "np=7.92 (mean)<BR>\n" );
document.write( "np(1-p)=variance=5.3064; sd is sqrt (V)=2.304<BR>\n" );
document.write( "Greater than 13 (or the same, which for a continuous function is essentially the same) is (13-7.92)/2.304=5.08/2.304=2.205<BR>\n" );
document.write( "P z>2.205 is 0.0137.<BR>\n" );
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document.write( "Can check with binomial<BR>\n" );
document.write( "24C13(.33)^13*(.67^11)=0.0168<BR>\n" );
document.write( "24C14(.33)^14(.67^10)=0.0065<BR>\n" );
document.write( "24C15(.33)^15(.67^9)=0.002<BR>\n" );
document.write( "Those 3 will be the major probabilities, and the exact binomial probability is 0.0235. </SPAN>\n" );
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