早上,农叔叔的店里起初玩具车的数量多于玩具船。 下午,他卖掉了玩具车数量的 12\frac{1}{2} 和 6 只玩具船。他没有卖完所有的玩具船。 下面的每个陈述要么是正确的,要么是错误的,要么是根据所给信息无法判断的。对于每个陈述,在正确的列中打勾(✓\checkmark)。
陈述正确错误无法确定
早上,农叔叔起初共有 13 辆玩具车和玩具船。
下午,农叔叔剩下的玩具车比玩具船多。
农叔叔剩下的玩具车和玩具船数量之间可能的最小差值是 5。

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完整解法

29

1. Establish the constraints for the number of toy cars and toy boats at first.

Let CC be the number of toy cars at first, and BB be the number of toy boats at first.
Given: C>BC > B.
He sold 12\frac{1}{2} of the toy cars, so CC must be an even number.
He sold 6 toy boats and did not sell all of them, so B>6B > 6. Since BB is an integer, B≥7B \ge 7.
Since C>BC > B and CC is even, the minimum possible value for CC is 8.

2. Evaluate the first statement: 'In the morning, Uncle Nong had a total of 13 toy cars and toy boats at first.'

Total at first = C+BC + B.
Minimum B=7B = 7.
Minimum C=8C = 8 (since C>BC > B and CC is even).
Minimum total = 8+7=158 + 7 = 15.
Since the minimum total is 15, it is impossible for the total to be 13.
Therefore, the statement is False.

3. Evaluate the second statement: 'In the afternoon, Uncle Nong had more toy cars than toy boats left.'

Cars left = 12C\frac{1}{2}C.
Boats left = B−6B - 6.
We need to compare 12C\frac{1}{2}C and B−6B - 6.
Case 1: Let C=8,B=7C = 8, B = 7. Cars left = 4, Boats left = 1. Here, 4>14 > 1 (More cars left).
Case 2: Let C=10,B=9C = 10, B = 9. Cars left = 5, Boats left = 3. Here, 5>35 > 3 (More cars left).
Case 3: Let C=20,B=19C = 20, B = 19. Cars left = 10, Boats left = 13. Here, 10<1310 < 13 (More boats left).
Since it can be either way depending on the initial numbers, it is Not possible to tell.

4. Evaluate the third statement: 'The least possible difference between the number of toy cars and toy boats Uncle Nong had left was 5.'

Difference = ∣12C−(B−6)∣|\frac{1}{2}C - (B - 6)|.
Let's try to find a case where the difference is less than 5.
From Case 2 above: C=10,B=9C = 10, B = 9. Cars left = 5, Boats left = 3. Difference = 5−3=25 - 3 = 2.
Since 2 is less than 5, the least possible difference is not 5 (it can be smaller, even 0 if 12C=B−6\frac{1}{2}C = B - 6, e.g., C=14,B=13C = 14, B = 13, cars left = 7, boats left = 7, difference = 0).
Therefore, the statement is False.

答案
StatementTrueFalseNot possible to tell
In the morning, Uncle Nong had a total of 13 toy cars and toy boats at first.✓\checkmark
In the afternoon, Uncle Nong had more toy cars than toy boats left.✓\checkmark
The least possible difference between the number of toy cars and toy boats Uncle Nong had left was 5.✓\checkmark

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