The length and breadth of a plate are  $\left(10\pm 0.1\right)\text{cm}$ and $\left(6\pm 0.2\right)cm$ respectively. The area of the plate is

  $A=lb$

$\frac{\Delta A}{A}=\frac{\Delta l}{l}+\frac{\Delta b}{b}\Rightarrow \Delta A=A\left(\frac{\Delta l}{l}+\frac{\Delta b}{b}\right)$ 

                                      $=60\left(\frac{0.1}{10}+\frac{0.2}{6}\right)$

                                      $=60\left(\frac{0.6+2}{60}\right)=2.6$

                $A\pm \Delta A=\left(60\pm 2.6\right)c{m}^2$