document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=275558>Question 275558</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The average age of a vehicle registered in the United States is 8 years, or 96 months. Assume the standard deviation is 16 months. If a random sample of 36 vehicles is selected, find the probability that the mean of their age is between 90 and 100 months. <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 #200971 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=200971\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The average age of a vehicle registered in the United States is 8 years, or 96 months. Assume the standard deviation is 16 months. If a random sample of 36 vehicles is selected, find the probability that the mean of their age is between 90 and 100 months. \r<BR>\n" );
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document.write( "Find the t-scores of 90 and 100.<BR>\n" );
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document.write( "t(90) = (90-96)/[16/sqrt(36)]<BR>\n" );
document.write( "= -6/(16/6) = - 2.25<BR>\n" );
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document.write( "t(100) = (100-96)/[16/36)] = 4*6/16 = 1.5<BR>\n" );
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document.write( "P(90 < t-bar < 100) = P(-2.25< t < 1.5) = tcdf(-2.25,1.5,35) = 0.9133<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
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