Karan, Arjun and Krunal alone can complete a work in 50,

Solution

Let the total work = 300 units (LCM of 50, 75 and 60) Amount of work done by Karan alone in one day = 300/50 = 6 units Amount of work done by Arjun alone in one day = 300/75 = 4 units Amount of work done by Krunal alone in one day = 300/60 = 5 units Amount of work done by Karan, Arjun and Krunal together in 9 days = 9 × (6 + 4 + 5) = 135 units Amount of work done by Arjun and Krunal together in 15 days = 15 × (4 + 5) = 135 units Remaining work = 300 – 135 – 135 = 30 units So, the time taken by Krunal alone to complete 30 units work = 30/5 = 6 days So, Krunal worked for 6 + 15 + 9 = 30 days