1952 AMC 12 第 4 题

Question

邮寄包裹的费用为

C

美分。包裹重

P

磅，且

P

是整数。第一磅收费

10

美分，此后每增加一磅收费

3

美分。费用公式为：

The cost

C

of sending a parcel post package weighing

P

pounds,

P

an integer, is

10

cents for the first pound and

3

cents for each additional pound. The formula for the cost is:

C=10+3P

C=10P+3

C=10+3(P-1)

C=9+3P

C=10P-7

只有第一磅以后的重量才按每增加一磅的费率收费

Only the pounds after the first are charged at the additional-pound rate

一个重

P

磅的包裹有

P-1

磅属于额外重量

A

P

-pound package has

P-1

additional pounds

第一磅收费

10

美分。其余

P-1

磅收费

3(P-1)

美分，所以

C=10+3(P-1)\text{。}

因此，正确答案是 C。

The first pound costs

10

cents. The remaining

P-1

pounds cost

3(P-1)

cents, so

C=10+3(P-1).

Thus, the correct answer is C.

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