document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=310138>Question 310138</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Twenty students randomly assigned to an experimental group receive an<BR>\n" );
document.write( "instructional program; 30 in a control group do not. After 6 months, both groups<BR>\n" );
document.write( "are tested on their knowledge. The experimental group has a mean of 38 on the<BR>\n" );
document.write( "test (with an estimated population standard deviation of 3); the control group<BR>\n" );
document.write( "has a mean of 35 (with an estimated population standard deviation of 5). Using<BR>\n" );
document.write( "the .05 level, what should the experimenter conclude? (a) Use the steps of<BR>\n" );
document.write( "hypothesis testing, (b) sketch the distributions involved, and (c) explain your<BR>\n" );
document.write( "answer to someone who is familiar with the t test for a single sample but not<BR>\n" );
document.write( "with the t test for independent means.<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 #221844 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=221844\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> 20 students randomly assigned to an experimental group receive an<BR>\n" );
document.write( "instructional program; 30 in a control group do not. <BR>\n" );
document.write( "After 6 months, both groups are tested on their knowledge. <BR>\n" );
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document.write( "The experimental group has a mean of 38 on the test (with an estimated population standard deviation of 3); <BR>\n" );
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document.write( "The control group has a mean of 35 (with an estimated population standard deviation of 5). <BR>\n" );
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document.write( "Using the .05 level, what should the experimenter conclude? <BR>\n" );
document.write( "(a) Use the steps of hypothesis testing, <BR>\n" );
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document.write( "Ho: u(ex)-u(ct) = 0<BR>\n" );
document.write( "Ha: u(ex)-u(ct) is not equal to zero<BR>\n" );
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document.write( "test stat: t = (38-35)/sqrt[9/20 + 25/30] = 2.6482<BR>\n" );
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document.write( "p-value = 2*P(t > 2.6482 with df = 48) = 0.0109<BR>\n" );
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document.write( "Conclusion:<BR>\n" );
document.write( "At the 5% significance level, reject Ho because the p-value<BR>\n" );
document.write( "is less than 5%.<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
document.write( "Note: I'll leave the remainder of the problem to you.<BR>\n" );
document.write( " \r<BR>\n" );
document.write( "<BR>\n" );
document.write( "<BR>\n" );
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document.write( "(b) sketch the distributions involved, and (c) explain your<BR>\n" );
document.write( "answer to someone who is familiar with the t test for a single sample but not<BR>\n" );
document.write( "with the t test for independent means.\r<BR>\n" );
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