设A、B、C.三个部门的人数为a、b、c,则有:
(38a + 24b)/(a + b)= 30
简化可得:a = 3b/4
(24b + 42c)/(b + c)= 34
简化可得:c = 5b/4
该单位全体人员的平均年龄 =(38a + 24b + 42c)/(a + b + c)= (38 x 3b/4 + 24b + 42 x 5b/4)/(3b/4 + b + 5b/4)= 105b / 3b = 35岁
应选择C.35
设A、B、C.三个部门的人数为a、b、c,则有:
(38a + 24b)/(a + b)= 30
简化可得:a = 3b/4
(24b + 42c)/(b + c)= 34
简化可得:c = 5b/4
该单位全体人员的平均年龄 =(38a + 24b + 42c)/(a + b + c)= (38 x 3b/4 + 24b + 42 x 5b/4)/(3b/4 + b + 5b/4)= 105b / 3b = 35岁
应选择C.35