document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1040374>Question 1040374</A>: <I><SPAN STYLE=\"word-break: break-all;\"> 9. (14 pts) Life expectancy at birth is the estimated lifespan of a baby born in a particular year (given the conditions of that time period).  Based on data retrieved from http://www.indexmundi.com/facts/united-states/life-expectancy-at-birth the following chart of U.S. life expectancy for males has been prepared.\r<BR>\n" );
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document.write( "img src= http://d2vlcm61l7u1fs.cloudfront.net/media%2F73f%2F73fe8e89-e840-4194-85c2-0c891fa17698%2FphpJRNuLz.png\r<BR>\n" );
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document.write( "The regression line is y = 0.2052x  – 336.5, where x = birth year and y = U.S. life male expectancy, in years. The value of r2 is 0.9809.\r<BR>\n" );
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document.write( "(a)  Use the regression line to estimate the U.S. life expectancy of a male baby born in 1970, to the nearest tenth of a year. Show some work.\r<BR>\n" );
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document.write( "(b)  Use the regression line to predict the U.S. life expectancy of a male baby born in 2020, to the nearest tenth of a year. Show some work.\r<BR>\n" );
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document.write( "(c)  What is the slope of the regression line and what are the units of measurement? In a sentence, interpret what the slope is telling us, in the context of this real-world application.\r<BR>\n" );
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document.write( "(d) What is the value of the correlation coefficient, r? Also, interpret its value: Looking at the graph and the size of r, do you judge the strength of the linear relationship to be very strong, moderately strong, somewhat weak, or very weak?  </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #655601 by </B><A HREF=/tutors/aboutme.mpl?userid=Boreal><B>Boreal(15235)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Boreal><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=Boreal><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=655601\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> y = 0.2052x – 336.5<BR>\n" );
document.write( "=(0.2052)(1970)-336.5=67.7 years<BR>\n" );
document.write( "y=(0.2052)(2020)-336.5=78.0 years<BR>\n" );
document.write( "slope of the line is 0.2052, and the units are rise/run which is age(in years)/year of birth<BR>\n" );
document.write( "The real-world application is that age of male children born increases 0.336.5, a third of a year, for every year their birth is delayed.  Or, male children born 10 years later will be expected to live about 3.4 years longer than their counterparts.<BR>\n" );
document.write( "r=sqrt(0.9809)=0.99.  This is a very high correlation and I would say the strength of the linear relationship is very strong. </SPAN>\n" );
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