【单选题】A restaurant orders 150 kg of pumpkins from the farmer's market. The farmer fills the order with 23 pumpkins. The average mass of the first 20 pumpkins is 6.5 kg. What must be the minimum average mass...
【简答题】One day a farmer’s donkey fell down into a well. The animal cried piteously for hours as the farmer tried to figure out what to do. Finally, he decided that the animal was old, and the well needed 31 ...