The correct preposition is "round" because it is commonly used when referring to sitting or gathering around an object, such as a table. This preposition implies that people are positioned in a circular or surrounding manner relative to the table.
Thus, the correct sentence is: "They were all sitting round the table."
Arun’s present age in years is 40% of Barun’s. In another few years, Arun’s age will be half of Barun’s. By what percentage will Barun’s age increase during this period?