A,B and C can complete a job in 10 days, working together. But only two of them can work together at a time. If all of them work for the same number of days with equal efficiency, how many days would each one have worked for when the job is completed?

Solution (By Examveda Team)

Let there be 30 units of work. Each day 3 units are completed. So each of A,B and C would do 1 unit per day. So, if A,B work on day 1 they would complete 2 units. Similarly, (B,C) and (C,A) do 2 units per day. So when the job is completed that is at the end of 15 days each one would have worked for 10 days.

Alternative method:
Since each one works for equal number of days they would each have done the same amount of work. Hence, they would each do 10 units, i.e. in 10 days.