(1) is a multiple of 2, a multiple of 3, which means it is a multiple of 6 and a multiple of 24, which means it may be 6,12,24. Going to primary school means that he can only be 12 years old.

(2) The total mass of apples is twice that of oranges, which means that the total mass of five boxes of fruits is three times that of oranges.

(17+20+25+17+23) ÷ 3 = 34kg, that is, the total mass of oranges is 34 kg, only 17+ 17=34.

Therefore, the weights of two baskets of oranges are 17kg and 17kg respectively.

(3) At present, there are 22 people in groups of three. At least two more people can get the average score, and at least 1 person can get the average score.

(4) The sum of these five digits is 35 1 (not necessarily accurate).

(5) Kindergarten has 158 children. If every two children are divided into groups, there is nothing to spare. If five people are in a group, there are extra ones. Because 158 is a multiple of 2 instead of 5.