Jack is a farmer and he wants to know the average weight of all the potatoes in a sack. He randomly selects 10 potatoes and weighs them. Their weights, to the nearest ounce are 5, 8, 9, 11, 7, 7, 8, 9, 12, and 7. What is the best estimate of the average weight of all the potatoes in the sack? Round to the nearest ounce.