Three processes A, B and C are admitted into the ready queue by the long-term scheduler. The processes are admitted -- first process C, then B, and then A -- without any delay between the admissions. The short-term scheduler uses a Round-Robin scheduling policy to assign processes to run on the CPU. The time quantum is  ns. The CPU burst times ns, ns and ns (for  A, B and C respectively) are all multiples of .  Assume , the processes make no I/O requests, and all of the processes successfully complete. You may also assume that no other processes or OS activity are important for your computations. 

Based only on the information given, which of the following formulae is the average wait time for these 3 processes? 

Hint: to deduce the correct average wait time, use 1) the correct formula for the average turnaround time from the last question, and 2) the relationship between turnaround times and wait times.