FUN FACTORY

How much do they weigh?

作者：teens

头脑风暴：圆球到底有多重？

Here are five balls. They have different weights — 1kg, 2kg, 3kg, 4kg and 5kg. Look at the pictures. Do you know the weight of each ball? How many striped (条纹的) balls should we put on the fourth scale (天平) to make it balanced (平衡的)?

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