Outdoor grows are a little unpredictable, I suppose in good conditions you could expect around 3 oz's per plant maybe a little more or less each, it would also depend on where and at what point in the year they were planted. One would also be assuming they were all females with those kind of calculations, and that the plants were managed well enough to keep pests and other natural bad factors at bay. If you were just using random seed and not feminized, which would be incredibly expensive in a situation (feminized seed is not that cheap nor have I ever heard of anyone ordering it in that kind of volume) that large you can only hope for roughly 50-60% of them to be female, which means half the crop would need to be removed at some point too. The more I think about it the more I realize it's pretty much impossible to answer this question accurately.