Question

Gilda 有一袋弹珠。她把其中 $20\%$ 给了朋友 Pedro。然后她把剩下弹珠的 $10\%$ 给了另一位朋友 Ebony。最后，她把袋中此时剩下弹珠的 $25\%$ 给了弟弟 Jimmy。Gilda 自己还剩原来那袋弹珠的百分之多少？

Gilda has a bag of marbles. She gives $20\%$ of them to her friend Pedro. Then Gilda gives $10\%$ of what is left to another friend, Ebony. Finally, Gilda gives $25\%$ of what is now left in the bag to her brother Jimmy. What percentage of her original bag of marbles does Gilda have left for herself?

$20$

$33\dfrac{1}{3}$

$38$

$45$

$54$

答案：E

知识点：百分数

难度评级：960

视频讲解：

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文字解答：

假设 Gilda 原来有 $100$ 颗弹珠。给 Pedro $20$ 颗后，还剩 $100 - 20 = 80$ 颗。

接着她给 Ebony $80 \times .1 = 8$ 颗，还剩 $80 - 8 = 72$ 颗。

最后她给 Jimmy $72 \times .25 = 18$ 颗，还剩 $72 - 18 = 54$ 颗，也就是原来的 $54\%$ 。

正确答案是 E。

Assume that Gilda starts off with $100$ marbles. After giving $20$ marbles to Pedro, she has $100 - 20 = 80$ marbles left.

She then gives $80 \times .1 = 8$ marbles to Ebony, with her having $80 - 8 = 72$ marbles left.

Finally, Gilda gives $72 \times .25 = 18$ marbles to Jimmy. She has a total of $72 - 18 = 54$ marbles left, which is $54\%$ of her original total.

Thus, the correct answer is E.

2019 AMC 8 第 8 题

答案：E

难度评级：960

视频讲解：

文字解答：

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