# TCP congestion problem

Consider an instance of TCP’s Additive Increase Multiplicative Decrease(AIMD) algorithm where the window size at the start of the slow start phase is 2 MSS and the threshold at the start of the first transmission is 8 MSS. Assume that a time out occurs during the fifth transmission. Find the congestion window size at the end of the tenth transmission.

I am bit confuse in this concept.
What I know :

Slow start and congestion avoidance are different.
Slow start is used in conjunction with congestion avoidance.

Window size for 1st transmission = 2 MSS
Window size for 2nd transmission = 4 MSS
Window size for 3rd transmission = 8 MSS threshold reached, increase linearly (according to AIMD)
Window size for 4th transmission = ?? MSS Window size for 5th transmission = ?? MSS
time out occurs, resend 5th with window size reduced to half (according to AIMD)
Window size for 5th transmission = ??? MSS

What will be the Window size for 4th transmission ? 9 MSS or 10 MSS
It means i want to ask you after threshold window size should increase linearly means it should increase by 1 MSS or 2 MSS ( 2 MSS is given in example ) ?

What will be window size for 5th transmission ? Will it be 1 MSS or 2 MSS ?

Please clear my concept. I am so confused.