Talk:Gold Mine/@comment-92.41.185.225-20130219072923/@comment-92.41.185.225-20130219080935

Wrong. The true break even time for level 10 mine is exactly 82 DAYS from when the upgrade is initiated. And for level 11 mine, it is exactly 78 DAYS.

In calculating the economic break even point for mine/collector upgrade, whether you have a third source of income (eg. by attacking someone) is irrelevant.

To compute the true cost of the an upgrade, we need to factor in two things:

1, the upgrade cost (measured in time),

2, the opportunity cost (measured in time)

The opportunity cost is what it is in the table but it should be doubled, due to losing 50% resources from other attackers.

The upgrade cost given is in terms of elixir, for which we need to convert into gold first. The math behind is quite complex, but the result is intuitive, the conversion rate is just 1:1

Using level 10 as example.

To recover 84000 gold in cost, you need 84000/((2500-2200)/2) hours which is 560 hours

To recover the opportunity cost in none production, you need (29 day and 8 hour) * 2,

Total is 82 days.