document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=309134>Question 309134</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Dave the jogger runs the same route every day (about 2.2 miles). On 18 consecutive days, he recorded the number of steps using a pedometer. The results were:\r<BR>\n" );
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document.write( "3,450   3,363   3,228   3,360   3,304   3,407   3,324   3,365   3,290<BR>\n" );
document.write( "3,289   3,346   3,252   3,237   3,210   3,140   3,220   3,103   3,129\r<BR>\n" );
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document.write( "(a) Construct a 95 percent confidence interval for the true mean number of steps Dave takes on his run. <BR>\n" );
document.write( "(b) What sample size would be needed to obtain an error of ± 20 steps with 95 percent confidence?<BR>\n" );
document.write( "(c) Using Excel, plot a line chart of the data. What does the data suggest about the pattern over time?<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 #221102 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=221102\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Dave the jogger runs the same route every day (about 2.2 miles). On 18 consecutive days, he recorded the number of steps using a pedometer. The results were: <BR>\n" );
document.write( "3,450 3,363 3,228 3,360 3,304 3,407 3,324 3,365 3,290<BR>\n" );
document.write( "3,289 3,346 3,252 3,237 3,210 3,140 3,220 3,103 3,129 <BR>\n" );
document.write( "(a) Construct a 95 percent confidence interval for the true mean number of steps Dave takes on his run.<BR>\n" );
document.write( "1st: find the mean of the sample = x-bar ; find the std = s<BR>\n" );
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document.write( "2nd: find standard error = E = 1.96*s/sqrt(18)<BR>\n" );
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document.write( "95% CI: x-bar - E < u < x-bar + E<BR>\n" );
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document.write( "(b) What sample size would be needed to obtain an error of ± 20 steps with 95 percent confidence?<BR>\n" );
document.write( "n = [1.96*s/20]^2<BR>\n" );
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document.write( "(c) Using Excel, plot a line chart of the data. What does the data suggest about the pattern over time?<BR>\n" );
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document.write( "I'll leave that plotting to you.<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H.<BR>\n" );
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