Hidden Markov Model

I am trying to find answers to the following questions. Can someone please help. This is a Hidden Markov Model with 7 states and 4 observations. I have worked out the following solution but still need help with parts ii iii.

Solution:

I. GATTAG = 1* 1 * 0.5 * 0.25 * 0.2 * 0.5 * 0.4 * 0.15 * 0.6 * 0.25 * 1 * 0.5 * 1 =0.00005625

II. GTAAG

possible paths: B - S1- S2 - S4 - S5 - S7- E

=1 * 1 * 0.5 * 0.5 * 0.4 * 0.4 * 0.6 * 0.25 * 1 * 0.5 * 1 =

B - S1- S2 - S4 - S6 - S7- E

= 1* 1 * 0.5 * 0.5 * 0.4 * 04 * 0.4 * 0 * 0.7 * 0.5 * 1 = 0

B - S1- S3- S4 - S6 - S7- E

= 0

B - S1- S3- S4 - S5 - S7- E

= 1 * 1 * 0.5 * 0.3 * 0.4 * 0.4 * 0.6 * 0.25 * 1 * 0.5 * 1 =

III. GTACGG

possible paths: B - S1- S2- S3- S4 - S6 - S7- E

B - S1- S2- S3- S4 - S5 - S7- E

B - S1- S3 - S2- S4 - S6 - S7- E

B - S1- S3 - S2- S4 - S5 - S7- E

B - S1- S3 - S3- S4 - S6 - S7- E

B - S1- S3 - S3- S4 - S5 - S7- E

B - S1- S3 - S4 - S6 - S6 - S7- E

B - S1- S2 - S4 - S6 - S6 - S7- E

How do I calculate this probability?