The length and breadth of a rectangular block are 25.2 cm and 16.8 cm,

1.	The length and breadth of a rectangular block are 25.2 cm and 16.8 cm, which have both been measured to an accuracy of 0.1 cm. find the area of the rectangular block.
Answer» Area of rectangular block = 25.2 × 16.8 = 423.4 cm² ∴ \(\frac{\Delta A}{A}=(\frac{\Delta l}{l}+\frac{\Delta b}{b})\) =\((\frac{0.1}{25.2}+\frac{0.1}{16.8})\) ∴ ΔA = \((\frac{0.1}{25.2}+\frac{0.1}{16.8})\times423.4\) = 4.2 cm² ∴ Area of rectangle block = (423.4 ± 4.2) cm²

The length and breadth of a rectangular block are 25.2 cm and 16.8 cm, which have both been measured to an accuracy of 0.1 cm. find the area of the rectangular block.

Answer»

Area of rectangular block

= 25.2 × 16.8

= 423.4 cm²

∴ \(\frac{\Delta A}{A}=(\frac{\Delta l}{l}+\frac{\Delta b}{b})\)

=\((\frac{0.1}{25.2}+\frac{0.1}{16.8})\)

∴ ΔA = \((\frac{0.1}{25.2}+\frac{0.1}{16.8})\times423.4\)

= 4.2 cm²

∴ Area of rectangle block

= (423.4 ± 4.2) cm²