If 8.5 m of a uniform rod weighs 30.6 kg, what will be the weight of 5 m of the same rod?

Weight of 8.5 m rod = 30.6 kg.

Weight of 1 m rod = $\Big(\dfrac{30.6}{8.5}\Big) \text{ kg} \quad \text{[Less length, Less weight]}$

Multiply by 10 to remove decimals.

Weight of 1 m rod = $\Big(\dfrac{30.6 \times 10}{8.5 \times 10}\Big) \text{ kg} = \Big(\dfrac{306}{85}\Big) \text{ kg}$

Weight of 5 m rod = $\Big(\dfrac{306}{85} \times 5\Big) \text{ kg} \quad \text{[More length, More weight]}$

= $\Big(\dfrac{306}{17}\Big) \text{ kg} \quad \text{(Dividing 5 and 85 by 5)}$

= 18 kg.

Hence, the weight of 5 m of the rod is 18 kg.