What is the minimum number of times one needs to measure to get 298 litres of water from a tank, if the measuring cylinders have capacities 1 litre, 6 litres, 25 litres and 100 litres?

Correct Answer: (B) 5

Using the available cylinder capacities of 1, 6, 25, and 100 litres: One can obtain 298 litres by filling the 100-litre cylinder 3 times ($3$$\times$ 100 = 300$\text{ litres}$) and removing 1 litre twice using the 1-litre cylinder ($300 - 2$$\times$ 1 = 298$\text{ litres}$). This requires $3 + 2 = 5$ measurements. Achieving 298 litres in 4 or fewer measurements is mathematically impossible with these capacities, making 5 the minimum number of measurements.