document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1040399>Question 1040399</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A survey of 800 women shoppers found that 17% of them shop on impulse. What is the 98% confidence interval for the true proportion of women shoppers who shop on impulse?<BR>\n" );
document.write( "A. 0.136 < p < 0.204<BR>\n" );
document.write( "B. 0.139 < p < 0.201<BR>\n" );
document.write( "C. 0.148 < p < 0.192<BR>\n" );
document.write( "D. 0.144 < p < 0.196 </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #655280 by </B><A HREF=/tutors/aboutme.mpl?userid=jim_thompson5910><B>jim_thompson5910(35256)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=jim_thompson5910><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=655280\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <font size=3 color=black><BR>\n" );
document.write( "Use <a  rel=nofollow HREF=\"http://www.sjsu.edu/faculty/gerstman/StatPrimer/t-table.pdf\">this table</a> (or similar) to find that the critical z value is  2.326\r<BR>\n" );
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document.write( "Look at the confidence level of 98% (bottom of page). Then look directly above it to find the value  2.326\r<BR>\n" );
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document.write( "So z =  2.326\r<BR>\n" );
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document.write( "Given information<BR>\n" );
document.write( "phat = 0.17<BR>\n" );
document.write( "n = 800\r<BR>\n" );
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document.write( "Standard Error:<BR>\n" );
document.write( "SE = sqrt(phat*(1-phat)/n)<BR>\n" );
document.write( "SE = sqrt(0.17*(1-0.17)/800)<BR>\n" );
document.write( "SE = 0.0132806249853\r<BR>\n" );
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document.write( "Margin of error<BR>\n" );
document.write( "ME = z*SE<BR>\n" );
document.write( "ME = 2.326*0.0132806249853<BR>\n" );
document.write( "ME = 0.0308907337158\r<BR>\n" );
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document.write( "Lower Bound (L) of the confidence interval<BR>\n" );
document.write( "L = phat - ME<BR>\n" );
document.write( "L = 0.17 - 0.0308907337158<BR>\n" );
document.write( "L = 0.1391092662842<BR>\n" );
document.write( "L = 0.139\r<BR>\n" );
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document.write( "Upper Bound (U) of the confidence interval<BR>\n" );
document.write( "U = phat + ME<BR>\n" );
document.write( "U = 0.17 + 0.0308907337158<BR>\n" );
document.write( "U = 0.2008907337158<BR>\n" );
document.write( "U = 0.201\r<BR>\n" );
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document.write( "The confidence interal is (L,U) = (0.139, 0.201) which is equilavent to saying L < p < U which turns into <font color=red size=5>0.139 < p < 0.201</font>\r<BR>\n" );
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document.write( "So the answer is choice <font color=red size=5>B) 0.139 < p < 0.201</font>\r<BR>\n" );
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document.write( "The population proportion p is somewhere between 13.9% and 20.1% and we're 98% confident of this fact.\r<BR>\n" );
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document.write( "</font> </SPAN>\n" );
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