document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=494598>Question 494598</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Two growth hormones are being considered. A random sample of 10 rats was given the first hormone and their average weight gain was x1 = 2.3 pounds with standard deviation s1 = 4 pound. For the second hormone, a random sample of 15 rats had an average weight gain of x2 = 1.9 pounds with standard deviation s2 = 0.2 pound. Assume the weight gains follow a normal distribution. Find a 90% confidence interval for the difference in average weight gain for the two growth hormones.<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 #335714 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=335714\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Two growth hormones are being considered. A random sample of 10 rats was given the first hormone and their average weight gain was x1 = 2.3 pounds with standard deviation s1 = 4 pound. For the second hormone, a random sample of 15 rats had an average weight gain of x2 = 1.9 pounds with standard deviation s2 = 0.2 pound. Assume the weight gains follow a normal distribution. Find a 90% confidence interval for the difference in average weight gain for the two growth hormones.<BR>\n" );
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document.write( "I worked out your problem without the calculator.<BR>\n" );
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document.write( "x-bar: 2.3-1.9 = 0.4<BR>\n" );
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document.write( "ME: 1.645*sqrt[(4^2/10) + (0.2^2/15)] = 2.08<BR>\n" );
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document.write( "90%CI: 0.4-2.08 < u1-u2 < 0.4+2.08<BR>\n" );
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document.write( "90%CI: -1.68 < u1-u2 < 2.48<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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document.write( "A. 0.20 to 0.60 pounds  <BR>\n" );
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document.write( " B. 0.17 to 0.63 pounds  <BR>\n" );
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document.write( " C. 0.15 to 0.65 pounds  <BR>\n" );
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document.write( " D. 0.24 to 0.56 pounds \r<BR>\n" );
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document.write( "I ran a 2-Sample T Interval TI-84 program and <BR>\n" );
document.write( "got the following interval:<BR>\n" );
document.write( "(-1.92,2.72)<BR>\n" );
document.write( "df = 9.03<BR>\n" );
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document.write( "A 2-Sample Z Interval gives the following interval:<BR>\n" );
document.write( "(-1.68,2.48)<BR>\n" );
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document.write( "If I were you I would doubt the \"answer\" choices<BR>\n" );
document.write( "you were given.<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "stan H.<BR>\n" );
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