题目

A group of friends on a hoke split up into smaller groups. When they formed groups of three, one person was left out. When they formed groups of four, two people were left out. When they formed groups of six, four people were left out. If the group contains at least a dozen people, what is the smallest possible number of people in the group?

选项

A.

10

B.

20

C.

22

D.

26

E.

34

解析

### 已知条件: 一群徒步的朋友分成小组。 - 3人一组时,余1人; - 4人一组时,余2人; - 6人一组时,余4人。 ### 问题: 若这群人至少有12个,求该群体最少有多少人? 设群体人数为\(x\),则: \(x = 3k + 1 = 4m + 2 = 6l + 4\)(其中\(k\)、\(m\)、\(l\)为整数),且\(x > 12\)。 求\(x\)的最小值。 #### 情况1: 联立\(3k + 1 = 4m + 2\),得\(3k - 4m = 1\)。 其整数解为\((k,m) = \{(3,2),(7,5),(11,8),...\}\),对应\(x = \{10, 22, 34,...\}\)。 #### 情况2: 联立\(4m + 2 = 6l + 4\),化简得\(2m - 3l = 1\)。 其整数解为\((l,m) = \{(2,1),(5,3),(8,5),...\}\),对应\(x = \{6,14,22,...\}\)。 两组解的公共值且大于12的最小数是22,验证: \(22 = 3×7 + 1 = 4×5 + 2 = 6×3 + 4\),满足所有条件。 因此,\(x\)的最小值为22。 答案:C
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