Hunterbunter, since this is your first time on the bounty list, please check that your address is correct at:
https://raw.github.com/Unthinkingbit/charity/master/bounty_31.csv

Hello, We are both correct.

Since the hashpower of the whole dvc network varies from time to time, one block is not accurately generated in 10 minutes, sometimes longer and sometimes shorter.
As you use 10 mins as one block time, And I using average time of the older blocks (e.g. 1000 blocks before today) as block time. these two method is both ok, and the result won't be too different, maybe in one or two days.