document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1204414>Question 1204414</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The effectiveness of a blood-pressure drug is being investigated. An experimenter finds that, on average, the reduction in systolic blood pressure is 54.2 for a sample of size 362 and standard deviation 17.4.\r<BR>\n" );
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document.write( "Estimate how much the drug will lower a typical patient's systolic blood pressure (using a 95% confidence level).\r<BR>\n" );
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document.write( "Enter your answer as a tri-linear inequality accurate to one decimal place (because the sample statistics are reported accurate to one decimal place). </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #840659 by </B><A HREF=/tutors/aboutme.mpl?userid=Theo><B>Theo(13342)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Theo><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=Theo><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=840659\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> sample size is 362.<BR>\n" );
document.write( "sample mean is 54.2<BR>\n" );
document.write( "sample stansard deviation is 17.4<BR>\n" );
document.write( "using the t-score, critical t-score with 361 degrees of freedom (sample size minus 1) is equal to plus or minus 1.9666.<BR>\n" );
document.write( "t-score formula is t = (x-m)/s<BR>\n" );
document.write( "t is the t-score<BR>\n" );
document.write( "x is the critical mean<BR>\n" );
document.write( "m is the sample mean<BR>\n" );
document.write( "s is the standard error\r<BR>\n" );
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document.write( "standard error = standard deviation / sqrt(sample size) = 17.4 / sqrt(362) = .9145.<BR>\n" );
document.write( "on the high side, t=(x-m)/s becomes 1.9666 = (x-54.2)/.9145.<BR>\n" );
document.write( "solve for x to get x = 1.9666 * .9145 + 54.2 = 55.9985<BR>\n" );
document.write( "on the low side, t = (x-m)/s becomes -1.9666 = (x-54.2)/.9245.<BR>\n" );
document.write( "solve for x to get x = -1.9666 * .9145 + 54.2 = 52.4015.<BR>\n" );
document.write( "round to 1 decimal place to get:<BR>\n" );
document.write( "the 95% confidence interval is between 52.4 and 56 points at 95% confidence level.<BR>\n" );
document.write( "your tri-linear equality would be 52.4 <= x <= 56.<BR>\n" );
document.write( "since the variable is continuous, then some sticklers will say 52.4 < x < 56 bcause the value can never be exactly a specific value.\r<BR>\n" );
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document.write( " </SPAN>\n" );
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