1996 AMC 12 第 2 题

Question

沃尔特每天做家务可得

\$3

，如果做得特别好则可得

\$5

。他连续

10

天每天都做家务，共收到

\$36

。沃尔特有多少天把家务做得特别好？

Each day Walter gets

\$3

for doing his chores or

\$5

for doing them exceptionally well. After

10

days of doing his chores daily, Walter has received a total of

\$36.

On how many days did Walter do them exceptionally well?

3

4

5

6

7

先计算十天全部按普通标准计酬时沃尔特能得到的钱数

Begin with the amount Walter would earn at the ordinary rate on all ten days

每个表现特别好的日子都会在这个基准上增加相同的钱数

Each exceptionally good day adds the same amount to that baseline

十个普通日子会得到

10\cdot3=30

美元。每个表现特别好的日子会多得

5-3=2

美元，而实际总额多出

6

美元。因此共有

\frac{6}{2}=3

个表现特别好的日子，所以正确答案是 A。

Ten ordinary days would pay

10\cdot3=30

dollars. Each exceptional day adds

5-3=2

dollars, and the actual total is

6

dollars higher. Thus there were

\frac{6}{2}=3

exceptional days, so the correct answer is A.

其他年份的第 2 题