Answer:
Size of groups known: First and last questions (The rice and cups ones)
Number of groups known: Second and third questions (Cars and hats)
Step-by-step explanation:
In the first problem, you know that one sack is one group, and it tells you that each sack weighs 3 kg. Therefore, you know the size of the group (or a sack).
In the last one, you know that a table is one group and each table fits 4 cups. So, you know that the size of the group is 4 cups.
In the second and third questions, you know that each group is a row (cars) or "equal group" (hat) and that there are 4 of each. So, you know that there are 4 of each group, meaning you know the "number of groups"
