Simulation doubt (or) plzz help

ICAI solution is similar to the solution in padhuka. Padhuka has mentioned the S.No of persons waiting.

For length of waiting line.I would suggest you to start looking at the solution from the end.See the arrival time of the last person, that is 11:57 check if any service end time for any persons before him is after 11:57, if not then there is no waiting line.

For the 17th person - arrival time 11:43 ,now search for service end time for persons before him after 11:43 ,you'll see that for 15th & 16th customer the service end time is 11:44 & 11:46, that is to say that he arrived before the above two persons left.So the length of waiting time is 2. :)

I secured 62 marks in AMA in Nov-14

ICAI solution 

Meaning of Length of waiting line "Is there any person before you in the line?"

Padhuka Solution

Meaning of Length of waiting line "How many people after you waiting in the line?"

Hope this would help :)

Thank you  Amar