AMC8 2008

AMC8 2008 · Q10

AMC8 2008 · Q10. It mainly tests Weighted average.

The average age of the $6$ people in Room A is $40$. The average age of the $4$ people in Room B is $25$. If the two groups are combined, what is the average age of all the people?

A 室 $6$ 人的平均年龄是 $40$。B 室 $4$ 人的平均年龄是 $25$。如果将两组人合并，所有人的平均年龄是多少？

(A) 32.5 32.5

(B) 33 33

(D) 34 34

(E) 35 35

Answer

Correct choice: (D)

正确答案：（D）

Solution

Answer (D): The sum of the ages of the 6 people in Room A is $6\times 40=240$. The sum of the ages of the 4 people in Room B is $4\times 25=100$. The sum of the ages of the 10 people in the combined group is $100+240=340$, so the average age of all the people is $\frac{340}{10}=34$.

答案（D）：A房间中6个人的年龄和为 $6\times 40=240$。B房间中4个人的年龄和为 $4\times 25=100$。合并后10个人的年龄总和为 $100+240=340$，因此所有人的平均年龄为 $\frac{340}{10}=34$。

Topics

AR.013 Weighted average