Read the passage given below and solve the questions based on it.
A group of 30 people can complete a job by working for 10 hours a day in 15 days. The group starts the work. But at the end of every day, starting from the first day, one person leaves the group and the remaining people work for 20 minutes less on the next day.
What part of the work, approximately remains to be done at the end of 15 days?