RRB Group-D Model Paper 16 with answers for online practice

Concept:
If 3 number A, B, and C are in proportion then
A/B = B/C
Where A, B, C are first, second, and third proportion respectively.Calculation:
Let the $3^{\mathit{r}\mathit{d}}$ proportional be A
∴ $\left({\mathit{x}}^2-{\mathit{y}}^2\right)$ /(x -y) = (x - y)/A
⇒ A = $\frac{{\left(\mathit{x}-\mathit{y}\right)}^2}{\left({\mathit{x}}^2-{\mathit{y}}^2\right)}$
Now, ${\mathit{x}}^2\mathit{–}{\mathit{y}}^2$ = (x – y)(x+y)
⇒A= $\frac{\left(\mathit{x}-\mathit{y}\right)\left(\mathit{x}-\mathit{y}\right)}{\left(\mathit{x}-\mathit{y}\right)\left(\mathit{x}+\mathit{y}\right)}$
⇒A= $\frac{\left(\mathit{x}-\mathit{y}\right)}{\left(\mathit{x}+\mathit{y}\right)}$