For HW13.2, I was using (5M shares /11)x2 but I am not sure if this is correct?

[NEAS: The denominator is too low, and you forgot to add 1 (to break ties).]

I think the problem with the question is that people are attacking the problem incorrectly.

I see the question as there's a board of directors that has X members, and some insurer with 5 million shares can (and will) elect 11 members of the X. So to elect two members of the X, one would need to have a similar proportion of votes for the X, namely:

(2 members of the board )*(5 million shares / 11 million members of the board) + 1 share in case of a tie = 909091 + 1 = 909092 votes.

I think in the bigger picture, the number of total seats in the board is insignificant, but with a share to board member ratio, the number of shares is easy to compute via dimensional analysis.

[NEAS: The number of seats is relevant.  You forgot to add 1 to the denominator.]