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NCERT Class XI Mathematics - Straight Lines - Solutions

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Question : 14 of 74
Marks: +1, -0
Consider the following population and year graph, find the slope of the line AB and using it, find what will be the population in the year 2010?
Solution:  
Slope of line AB = 97−921995−1985\frac{97-92}{1995-1985} = 12\frac{1}{2}
Let the population in year 2010 is y, and co-ordinate of C is (2010, y) then, slope of AB = slope of BC
⇒ 12\frac{1}{2} = y−972010−1995\frac{y-97}{2010-1995} ⇒ 12\frac{1}{2} = y−9715\frac{y-97}{15}
⇒ 15 = 2y – 194 ⇒ 2y = 209 ⇒ y = 104.5
Hence, the population in year 2010 will be 104.5 crores.
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