作者ififif (984 74 )
看板GRE_Verbal
標題Re: [數學] 兩題來欣M6的數學題
時間Mon Jul 2 12:52:56 2007
※ 引述《hjung (D~~~~~~!!)》之銘言：
: 1. Which of the following CANNOT yield an integer when divided by 10?
: (A) The sum of two odd integers
: (B) An integer less than 10
: (C) The product of two primes
: (D) The sum of three consecutive integers
: (E) An odd integer
: 答案是(E)
: 我用刪去法到最後剩下(B)跟(E)，可是想不出來為什麼最後要選(E)
(B) 要考慮 negative integers, such as -10, -20, etc.
: 2. A certain clock marks every hour by striking a number of times equal to
: the hour, and the time required for a stroke is exactly equal to the time
: interval between strokes. At 6:00 the time lapse between the beginning of
: the first stroke and the end of the last stroke is 22 seconds. At 12:00,
: how many seconds elapse between the beginning of the first stroke and the
: end of the last stroke?
: 答案是46秒
六點敲了六下，而敲一下的時間又等於間隔的時間
假設敲一下的時間 = 間隔的時間 = X
又 敲六下有五次間隔
所以 (6+5)*X = 22
X = 2
12點要敲12下 有11次間隔
所以 (12+11)*2 = 46
--
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◆ From: 210.69.128.66
1F：推 philistine:CANNOT yield an integer是指會整除嗎? 218.161.60.185 07/02 13:07
2F：推 philistine:還是不能被整除呢? 218.161.60.185 07/02 13:11
3F：推 philistine:B也有可能是０ 218.161.60.185 07/02 13:15
4F：→ philistine:我剛查了一下,是後者 218.161.60.185 07/02 13:16
5F：推 ififif:可以被10整除 210.69.128.66 07/02 13:18
6F：→ ififif:恩 (B) 0 也可以 210.69.128.66 07/02 13:18
7F：推 philistine:C是否可舉個例呢, 218.161.60.185 07/02 13:20
8F：推 ififif:5*(任意質數) 210.69.128.66 07/02 13:22
9F：推 philistine:我搞混了@@ 218.161.60.185 07/02 13:27
10F：→ philistine:CANNOT yield an integer是 218.161.60.185 07/02 13:27
11F：→ philistine:可以被10整除？ 218.161.60.185 07/02 13:27
12F：→ philistine:那B不就可以選了嗎?.? 218.161.60.185 07/02 13:28
13F：推 ififif:喔 抱歉 我會錯你的意思 是不能被10整除 210.69.128.66 07/02 13:36
14F：推 philistine:請問那5*11=55..55不是不能被10整除嗎? 218.161.60.185 07/02 13:40
15F：推 philistine:我忽略了2的存在orz...2*5=10可被整除 218.161.60.185 07/02 13:51
16F：推 ififif:抱歉 剛考完試頭昏昏的 應該只有5*2 210.69.128.66 07/02 14:07
17F：推 philistine:不會啦,很感謝你的熱心討論 218.161.60.185 07/02 14:12
18F：推 hjung:謝謝~原來我第二題會錯意了...||| 218.166.103.55 07/02 16:08