Question

Consider the given population and year graph. Find the slope of the line AB and using it, find what will be the population in the year 2010?

Answer 1

Since line AB passes through points A (1985, 92) and B (1995, 97), its slope is

$\frac { 97-92}{1995-1985}=\frac {5}{10}=\frac 12$

Let y be the population in the year 2010. Then, according to the given graph, line AB must pass through point C (2010, y).

∴ Slope of AB = Slope of BC

⇒ $\frac {1}{2} = \frac {y-97}{2010-1995}$

⇒ $\frac 12=\frac {y-97}{15}$

⇒ $\frac {15}{2}=y-97$

⇒ $y-97=7.5$

⇒ $y=7.5+97=104.5$

Thus, the slope of line AB is $\frac 12$, while in the year 2010, the population will be 104.5 crores.