Where to start on SJF Cpu schedualing homework problem? So the question is;

For the following three jobs:
P1: 10 (3,2,5); P2: 4 (2,2); P3: 16 (2,3,5,6)
Execute the three jobs using Exp Ave Alpha =0.6, default=2

I know the formula to get the exponential average for a process is 

Pn+1 = (alpha) * Tn + (1-alpha * Pn)

I am basically confused at where to start. Obviously, the value .6 gets plugged in for the alpha, but where does the 2 go in the formula? And with each iteration is N increased? Where do the first time quantum for each process (3, 2, 2) go into the equation?

I have searched all over the web for an explanation, but every video I see on SJF has a gant chart and is given arrival time and looks nothing like this problem.
Alright, so after reviewing with the professor, this is how this actually works.

The default of 2 means they all have an equal priority and just get run in order; process P1, P2, and P3.

Now, once we see P1 run for 3 quantums after the first burst, then we calculate its new prediction.

(0.6) * 2 [original default] + (0.4) * 3 [last run] = 1.2 + 1.2 = Prediction of 2.4

Same thing with P2 &amp; P3 (both have a first burst of 2 quantums.)

(0.6) * 2 [original default] + (0.4)* 2 [last run] = 1.2 + 0.8 = Prediction of 2.0

So for the next quantums' order, it would be P2, P3, THEN P1.

Then after that run you would just do;

(0.6) * [2nd to last burst] + (0.4) * [last burst] = new prediction to figure out which proces would run next.

So the actual order would be;

Quantum: Process

Q3: P1:3 

Q5: P2:2 

Q7: P3:2 

Q8: P2:2 (FINISHES) 

Q12: P3:3 

Q14: P1:2 

Q19: P3:5 

Q24: P1:5 (FINISHES) 

Q30: P3:6 (FINISHES)