Starting from the centre of the earth having radius R, the variation of g (acceleration due to gravity) is shown by

The value of g at a distance r < R is 

${\mathrm{g}}_{\text{inside }}=\left(\frac{\mathrm{GM}}{{\mathrm{R}}^3}\right)\mathrm{r}$

$\Rightarrow$The value of g increases at a constant rate and graph will be a straight line. 

The value of g at a distance r > R is 

${\mathrm{g}}_{\text{outide }}=\left(\frac{\mathrm{GM}}{{\mathrm{r}}^2}\right)$

$\Rightarrow$The value of g for r > R will be decreasing and the graph will be of a decreasing curve