document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1128508>Question 1128508</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Assume that a sample is used to estimate a population proportion (p). Find the Margin of Error (E) that corresponds to the given statistics and confidence level. Round the margin of error 4 decimal places.<BR>\n" );
document.write( "90% confidence, n= 300, x=140\r<BR>\n" );
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document.write( "I attempted to find p by dividing x/n and got 0.4666667, ad used that to get 1 which i got 0.54 from but when i did the equation it gave me 0.09xxxx which is not even close to the answers I had to choose from :(.  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #744979 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=744979\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <font color=\"black\" face=\"times\" size=\"3\"><BR>\n" );
document.write( "At 90% confidence, the critical z value is approximately 1.645\r<BR>\n" );
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document.write( "How to get this critical value? By looking up a table of values such as <a  rel=nofollow HREF= \"http://www.sjsu.edu/faculty/gerstman/StatPrimer/t-table.pdf\">this one</a>. For that specific table, look at the bottom row that starts with z. Right above the \"90% confidence level\" we see the value 1.645, which means that 90% of the area is between -1.645 and 1.645 under the normal curve. A table such as the one mentioned should be found in your book (likely the appendix). You can also opt to use a calculator to compute the critical z value through the use of the invNorm function on TI83 and TI84 calculators. \r<BR>\n" );
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document.write( "With z = 1.645, we can find the margin of error E using the formula below<BR>\n" );
document.write( "E = z*sqrt(phat*(1-phat)/n)<BR>\n" );
document.write( "where<BR>\n" );
document.write( "phat = x/n = 140/300 = 0.4666667\r<BR>\n" );
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document.write( "So,<BR>\n" );
document.write( "E = z*sqrt(phat*(1-phat)/n)<BR>\n" );
document.write( "E = 1.645*sqrt(0.4666667*(1-0.4666667)/300)<BR>\n" );
document.write( "E = 0.04738141553989<BR>\n" );
document.write( "E = 0.0474\r<BR>\n" );
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document.write( "Answer: 0.0474<BR>\n" );
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