AMC12 2009 B

AMC12 2009 B · Q3

AMC12 2009 B · Q3. It mainly tests Fractions, Percent.

Twenty percent less than 60 is one-third more than what number?

比 $60$ 少 $20\%$ 的数，比哪个数多三分之一？

(A) 16 16

(B) 30 30

(D) 36 36

(E) 48 48

Answer

Correct choice: (D)

正确答案：（D）

Solution

Twenty percent less than 60 is $\frac 45 \cdot 60 = 48$. One-third more than a number n is $\frac 43n$. Therefore $\frac 43n = 48$ and the number is $\boxed {36}$. The answer is $\mathrm{(D)}$.

比 $60$ 少 $20\%$ 是 $\frac 45 \cdot 60 = 48$。比一个数 $n$ 多三分之一是 $\frac 43n$。因此 $\frac 43n = 48$，这个数是 $\boxed {36}$。答案是 $\mathrm{(D)}$。

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