AMC12 2006 A

AMC12 2006 A · Q3

AMC12 2006 A · Q3. It mainly tests Ratios & proportions.

The ratio of Mary's age to Alice's age is $3:5$. Alice is $30$ years old. How old is Mary?

Mary的年龄与Alice的年龄之比为$3:5$。Alice今年$30$岁。Mary今年多少岁？

(A) 15 15

(B) 18 18

(D) 24 24

(E) 50 50

Answer

Correct choice: (B)

正确答案：（B）

Solution

Let $m$ be Mary's age. Then $\frac{m}{30}=\frac{3}{5}$. Solving for $m$, we obtain $m=\boxed{\textbf{(B) }18}.$

设$m$为Mary的年龄，则$\frac{m}{30}=\frac{3}{5}$。解得$m=\boxed{\textbf{(B) }18}.$

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