0.1 and 5/8 of a bamboo are in mud and water respectively and the rest length 2.75 m is above water. What is the length of the bamboo ?

Answer: Option A

$$\text{0}\text{.1 = }\frac{1}{10}\left(\text{mud}\right),\frac{5}{8}\left(\text{water}\right)$$
Let total length of bamboo = 40x ( LCM of 8, 10 )
$$\begin{array}{rl}& \text{Mud part :}\\ & \text{ = }\frac{1}{10}\times 40x=4x\\ & \text{Water part :}\\ & \text{ = }\frac{5}{8}\times 40x=25x\\ & \text{Remaining part :}\\ & =(40x-25x-4x)\\ & =11x\\ & 11x\to 2.75m\\ & x\to 0.25m\\ & 40x\to 10m\end{array}$$