AMC8 2008

AMC8 2008 · Q5

AMC8 2008 · Q5. It mainly tests Rates (speed), Arithmetic misc.

Barney Schwinn notices that the odometer on his bicycle reads $1441$, a palindrome, because it reads the same forward and backward. After riding $4$ more hours that day and $6$ the next, he notices that the odometer shows another palindrome, $1661$. What was his average speed in miles per hour?

Barney Schwinn 注意到他的自行车里程表显示 $1441$，这是一个回文数，因为正读反读都一样。那天他又骑了 $4$ 小时，第二天骑了 $6$ 小时后，他注意到里程表又显示另一个回文数 $1661$。他的平均速度是多少英里每小时？

(A) 15 15

(B) 16 16

(D) 20 20

(E) 22 22

Answer

Correct choice: (E)

正确答案：（E）

Solution

Answer (E): Barney rides $1661-1441=220$ miles in $10$ hours, so his average speed is $\frac{220}{10}=22$ miles per hour.

答案（E）：Barney 行驶了 $1661-1441=220$ 英里，用了 $10$ 小时，所以他的平均速度是 $\frac{220}{10}=22$ 英里/小时。

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