2000 AMC 12 第 3 题

Question

Jenny 每天吃掉当天开始时罐子里软糖的

20\%

。第二天结束时还剩

32

颗。罐子里原来有多少颗软糖？

Each day, Jenny ate

20\%

of the jellybeans that were in her jar at the beginning of that day. At the end of the second day,

32

remained. How many jellybeans were in the jar originally?

40

50

55

60

75

每天吃掉

20\%

，所以每天结束时剩下

80\%

。

Eating

20\%

leaves

80\%

at the end of each day

两天后剩下原数量的

(0.8)^2

。

After two days,

(0.8)^2

of the original amount remains

每天吃掉

20\%

，所以每天结束时剩下

80\%

。若原来有

x

颗，则

(0.8)^2 x = 32\text{。}

解得

0.64x = 32

，所以

x = 50

。

因此，正确答案是 B。

Since

20\%

is eaten each day,

80\%

remains at the end of each day. If

x

is the original number, then

(0.8)^2 x = 32.

Solving gives

0.64x = 32,

so

x = 50.

Thus, the correct answer is B.

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