AMC10 2014 B

AMC10 2014 B · Q8

AMC10 2014 B · Q8. It mainly tests Unit conversion, Rates (speed).

A truck travels $\frac{b}{6}$ feet every $t$ seconds. There are 3 feet in a yard. How many yards does the truck travel in 3 minutes?

一辆卡车每 $t$ 秒行驶 $\frac{b}{6}$ 英尺。1 码 = 3 英尺。卡车在 3 分钟内行驶多少码？

(A) $\frac{b}{1080t}$ $\frac{b}{1080t}$

(B) $30\frac{t}{b}$ $30\frac{t}{b}$

(D) $10\frac{t}{b}$ $10\frac{t}{b}$

(E) $10\frac{b}{t}$ $10\frac{b}{t}$

Answer

Correct choice: (E)

正确答案：（E）

Solution

The truck travels for $3 \cdot 60 = 180$ seconds, at a rate of $\frac{b}{6t} \cdot \frac{1}{3}$ yards per second. Hence the truck travels $180 \cdot \frac{b}{6t} \cdot \frac{1}{3} = 10\frac{b}{t}$ yards.

卡车行驶 $3 \cdot 60 = 180$ 秒，速度为 $\frac{b}{6t} \cdot \frac{1}{3}$ 码/秒。因此总距离为 $180 \cdot \frac{b}{6t} \cdot \frac{1}{3} = 10\frac{b}{t}$ 码。

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