Why is the average rating only 8.8 according to T-250?

Rating: 10/10 (28 December 2003)

This whole calculation of IMDb is driving me crazy.
They publish an equation to calculate the exact rating average which affect its position on IMDb's top 250 which is:
(v º (v+m)) ª R + (m º (v+m)) ª C
where:
R = average for the movie (mean) = (Rating)
v = number of votes for the movie = (votes)
m = minimum votes required to be listed in the top 250 (1250 for now)
C = the mean vote across the whole report (6.9 for now)
I tried to calculate it using the current votes and mean rating (which is for now (December 28th) 27778 votes and 9.4 rating average).
And that's what I came up with: (27778:(27778+1250)) X 9.4 + (1250: 27778+1250) X 6.9 which is: 8.9952 + 0.2971 = 9.2923 = ~9.3

That means it's supposed to be #1 with 9.3 rating average.
Nevertheless more than 70% of the users voted 10 comparing to the current #1 (Grandfather, The (1972)) which only 51.7% of the users voted 10 (note that close to 5000 users voted 1 and has only 8.5 Arithmetic mean rating).
For your consideration.