Question

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?

Answer 1

The points on the line are A(1985, 92) and B(1995, 97).

$\therefore$ Slope of $AB=\frac{97-92}{1995-1985}=\frac{5}{10}=\frac{1}{2}$

Let the population in year 2010 be x crores.

Then C(2010, x) lies on the line.

$\therefore$ Slope of $BC=\frac{y-97}{2010-1995}=\frac{y-97}{15}$

Since points A, B and C lie on a line,

$\therefore$ Slope of AB = Slope of BC

$\therefore \frac{1}{2}=\frac{y-97}{15}\Rightarrow 15=2y-194$

$\Rightarrow 2y=209\Rightarrow y=\frac{209}{2}=104.5$

Thus population in 2010 will be 104.5 crores.