AMC10 2000 A

AMC10 2000 A · Q3

AMC10 2000 A · Q3. It mainly tests Fractions, Interest / growth (simple).

Each day, Jenny ate 20% of the jellybeans that were in her jar at the beginning of that day. At the end of second day, 32 remained. How many jellybeans were in the jar originally?

每天，Jenny吃掉她罐子开始那天20%的果冻豆。到第二天结束时，还剩32颗。最初罐子里有多少果冻豆？

(A) 40 40

(B) 50 50

(D) 60 60

(E) 75 75

Answer

Correct choice: (B)

正确答案：（B）

Solution

Answer (B): Since Jenny ate $20\%$ of the jellybeans remaining each day, $80\%$ of the jellybeans are left at the end of each day. If $x$ is the number of jellybeans in the jar originally, then $(0.8)^2x=32$. Thus $x=50$.

答案（B）：因为珍妮每天吃掉剩余果冻豆的 $20\%$，所以每天结束时还剩下 $80\%$ 的果冻豆。若 $x$ 是罐子里最初的果冻豆数量，则 $(0.8)^2x=32$。因此 $x=50$。

Topics