2014 AMC 10B 第 1 题

Question

Leah 有

13

枚硬币，全部是一美分硬币和五美分硬币。如果她再多一枚五美分硬币，那么两种硬币的数量就相同。Leah 的硬币共值多少美分？

Leah has

13

coins, all of which are pennies and nickels. If she had one more nickel than she has now, then she would have the same number of pennies and nickels. In cents, how much are Leah’s coins worth?

33

35

37

39

41

答案：C

知识点：一次方程钱币

难度评级：560

小提示：

把“再多一枚五美分硬币”转化成关于两种硬币数量的方程。

Translate the nickel condition into an equation for pennies and nickels

大提示：

求出两种硬币数量后，使用总数

13

。

Use the total of

13

coins after finding the two counts

解答：

设一美分硬币有

p

枚，则五美分硬币有

13-p

枚；按题意，五美分硬币数也等于

p-1

，所以

13-p=p-1

。因此有

7

枚一美分硬币和

6

枚五美分硬币。

硬币的总价值为

7+6\cdot 5=37

美分。

所以正确答案是 C。

Let the number of pennies be

p.

Then, the number of nickels is

13-p

and

p-1,

so

13-p=p-1.

This means we have

7

pennies and

6

nickels.

Therefore, the number of cents is

7+6\cdot 5=37.

Thus, the correct answer is C .

2014 AMC 10B 第 1 题

答案：C

难度评级：560

小提示：

大提示：

解答：

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