Directions : Answer the question independently. A certain amount of work can be completed by 20 people in 100 days, working 12 hours a day. 5 people started the work, and starting from the second day, 7 people joined each day. Every alternate day, starting from the third day, two people left. If each person worked for two hours per day, then what fraction of the work was not completed after 60 days? (Assume efficiency of each person is the same)