Re: [數學] 兩題來欣M6的數學題
※ 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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推
07/02 13:07, , 1F
07/02 13:07, 1F
推
07/02 13:11, , 2F
07/02 13:11, 2F
推
07/02 13:15, , 3F
07/02 13:15, 3F
→
07/02 13:16, , 4F
07/02 13:16, 4F
推
07/02 13:18, , 5F
07/02 13:18, 5F
→
07/02 13:18, , 6F
07/02 13:18, 6F
推
07/02 13:20, , 7F
07/02 13:20, 7F
推
07/02 13:22, , 8F
07/02 13:22, 8F
推
07/02 13:27, , 9F
07/02 13:27, 9F
→
07/02 13:27, , 10F
07/02 13:27, 10F
→
07/02 13:27, , 11F
07/02 13:27, 11F
→
07/02 13:28, , 12F
07/02 13:28, 12F
推
07/02 13:36, , 13F
07/02 13:36, 13F
推
07/02 13:40, , 14F
07/02 13:40, 14F
推
07/02 13:51, , 15F
07/02 13:51, 15F
推
07/02 14:07, , 16F
07/02 14:07, 16F
推
07/02 14:12, , 17F
07/02 14:12, 17F
推
07/02 16:08, , 18F
07/02 16:08, 18F
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