document.write( "Question 554238: In 1991, the life expectancy of males in a certain country was 61.5 years. In 1995, it was 64.4 years. Let E represent the life expectancy in year t and let t represent the number of years since 1991. The linear function E(t) that fits the data is? \n" ); document.write( "

Algebra.Com's Answer #361287 by josmiceli(19441) $\"\"$ $\"About$

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A linear function means it is a straight line
\n" ); document.write( "Plot $\"+t+\"$ on the horizontal axis
\n" ); document.write( "Plot $\"+E+\"$ on the vertical axis
\n" ); document.write( "You are given the points:
\n" ); document.write( "( 0,61.5 ) and
\n" ); document.write( "( 4,64.4 )
\n" ); document.write( "--------
\n" ); document.write( "Use the point-slope formula:
\n" ); document.write( " $\"+%28+E+-+61.5+%29+%2F+%28+t+-+0+%29+=+%28+64.4+-+61.5+%29+%2F+%28+4+-+0+%29+\"$
\n" ); document.write( " $\"+%28+E+-+61.5+%29+%2F+t+=+2.9+%2F+4+\"$
\n" ); document.write( "Multiply both sides by $\"+4t+\"$
\n" ); document.write( " $\"+4%2A%28+E+-+61.5+%29+=+2.9t+\"$
\n" ); document.write( " $\"+4E+-+246+=+2.9t+\"$
\n" ); document.write( " $\"+4E+=+2.9t+%2B+246+\"$
\n" ); document.write( " $\"+E%28t%29+=+.725t+%2B+61.5+\"$
\n" ); document.write( "check answer:
\n" ); document.write( " $\"+E%280%29+=+.725%2A0+%2B+61.5+\"$
\n" ); document.write( " $\"+E%280%29+=+61.5+\"$
\n" ); document.write( "and
\n" ); document.write( " $\"+E%284%29+=+.725%2A4+%2B+61.5+\"$
\n" ); document.write( " $\"+E%284%29+=+2.9+%2B+61.5+\"$
\n" ); document.write( " $\"+E%284%29+=+64.4+\"$
\n" ); document.write( "OK \n" ); document.write( "

\n" );