A $10 bill(1,000 cents) was replaced with 50 coins having the same total value. The only coins used were 5-cent答案解析-雷哥GMAT

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A $10 bill(1,000 cents) was replaced with 50 coins having the same total value. The only coins used were 5-cent coins, 10-cent coins, 25-cent coins. and 50-cent coins. How man 5-cent coins were used?

(1) Exactly 10 of the coins were 25-cent coins and exactly 10 of the coins were 50-cent coins.

(2)The number of 10-cent coins was twice the number of 5-cent coins.

A

Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
分析A选项
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B

Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
分析B选项
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C

BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
分析C选项
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D

EACH statement ALONE is sufficient.
分析D选项
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E

Statements (1) and (2) TOGETHER are NOT sufficient.
分析E选项
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当前版本由 xxxxiao 更新于2019-12-17 18:30:57 感谢由 xxxxiao 对此题目的解答所做出的贡献。

设5-cent coins为x个

1：25*10+50*10+10*(30-x)+5*x=1000

x=10

充分

2：10-cent=2x

25-cent 和50-cent coins一共为50-3x个。无法确定25-cent 和50-cent分别有几个。无法确定x。不充分

题目讨论（5条评论）

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403045wqua

娘的漏了总共50个coins

2 0 回复 2022-08-06 15:04:53
985191kzkq回复403045wqua

娘的我也是

0 0 回复 2022-09-11 17:32:09

送我上700

条件2）设5cents 有a，25cents有b；5a+20a+25b+2500-150a-50b=1000
最后5a+b=60
b可以等于5.10.15...只要保证a是大于5的就行

0 回复 2022-06-21 19:40:24

贾思敏

A $10 bill(1,000 cents) was replaced with 50 coins having the same total value. The only coins used were 5-cent coins, 10-cent coins, 25-cent coins. and 50-cent coins. How many 5-cent coins were used?
分析题干：①1,000cents要换成50个coins（就是50个coins加起来要等于1,000cents）/ ②兑换用的coins的面值是5-cents、10-cent、25-cent和50-cent/ ③问面值为5-cent的coins有多少个?

一般，问题问什么你就设什么，设5-cent的coins有x个

(1) Exactly 10 of the coins were 25-cent coins and exactly 10 of the coins were 50-cent coins.
条件一：10*25+10*50+5x+(50-10-10-x)*10=1,000 一个一元一次方程，答案确定唯一，充分。

(2)The number of 10-cent coins was twice the number of 5-cent coins.
只知道10-cent和5-cent的数量关系，其他的50-cent和25-cent的数量未知，不充分。

错题反思：尼玛，我是眼瞎了才没发现第一个是一元一次方程，要转化成数学语言，列好等式啊！

0 回复 2021-10-09 16:55:20