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問題一在檔案裡
84.7517-!-item-!-187;#058&005572
If p is a prime number greater than 2, what is the value of p ?
(1)There are a total of 100 prime numbers between 1 and p + 1.
問題2.我的理解是他有100個值因數的加總會介於1~p+1之間所以一定會有這個數不曉得對不對?
(2)There are a total of p prime numbers between 1 and 3,912.
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【答案】D
【思路】
(1) 從1開始署到第101(2不是)的質數即是p←選項(1)成立(和思路不一樣)
(2) 數1~3912有幾個質數，即可得知p ←選項(2)成立
90.8266-!-item-!-187;#058&005947
On Jane's credit card account, the average daily balance for a 30-day billing cycle is the average (arithmetic mean) of the daily balances at the end of each of the 30 days.At the beginning of a certain 30-day billing cycle, Jane's credit card account had a balance of $600.Jane made a payment of $300 on the account during the billing cycle.If no other amounts were added to or subtracted from the account during the billing cycle, what was the average daily balance on Jane's account for the billing cycle?
(1)Jane's payment was credited on the 21st day of the billing cycle.
(2)The average daily balance through the 25th day of the billing cycle was $540.
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【答案】D
【思路】平均值=
(每天的餘額平均，昨天的期末於今天的期初餘額)，求平均值。已知:1.d1=600，其中dn=-300。且其中無任何金額變動。
(1) 300元是在第21天中付出，所以可得知1~20天每日餘額是600，21~30每日餘額是300即可求總平均值←選項(1)成立
(2)
=540且300是在第25天以前付掉(因期初為600)，第26~30天每日餘額為540( 問題三.300元已在25天錢花掉換句話說26~30的每日餘額不是剩300??) ，即可求總平均值，←選項(2)成立
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93.8525-!-item-!-187;#058&006006
If the integer n is greater than 1, is n equal to 2 ?
(1) n has exactly two positive factors.
(2)The difference of any two distinct positive factors of n is odd.
(問題四.我的理解是 N的”任”兩個因數的差是奇數所以B不成立我理解錯了嗎?)
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【答案】B
【思路】若兩數相減為奇數，則兩數必為一奇數，一偶數。
兩奇數或兩偶數相減都會是偶數。
(1) n有兩個正因數à只能得知n是個質數。
(2) n = 2 時，兩因數相減的結果有 2 – 1 = 1，2 – (-1) = 3，(-2) – 1 = -3，(-2) - (-1) = -1 四種，全是奇數。
n若n > 2，為偶數：n - 2 會是偶數。
n若n > 2，為奇數：n - 1 會是偶數。
由以上推理可知2是符合條件要求的唯一數字，故條件充分。
感謝戰友們!!
84.7517-!-item-!-187;#058&005572
If p is a prime number greater than 2, what is the value of p ?
(1)There are a total of 100 prime numbers between 1 and p + 1.
問題2.我的理解是他有100個值因數的加總會介於1~p+1之間所以一定會有這個數不曉得對不對?
(2)There are a total of p prime numbers between 1 and 3,912.
--------------------------------------------------------------------------------------------------------------------------------------------------------
【答案】D
【思路】
(1) 從1開始署到第101(2不是)的質數即是p←選項(1)成立(和思路不一樣)
(2) 數1~3912有幾個質數，即可得知p ←選項(2)成立
90.8266-!-item-!-187;#058&005947
On Jane's credit card account, the average daily balance for a 30-day billing cycle is the average (arithmetic mean) of the daily balances at the end of each of the 30 days.At the beginning of a certain 30-day billing cycle, Jane's credit card account had a balance of $600.Jane made a payment of $300 on the account during the billing cycle.If no other amounts were added to or subtracted from the account during the billing cycle, what was the average daily balance on Jane's account for the billing cycle?
(1)Jane's payment was credited on the 21st day of the billing cycle.
(2)The average daily balance through the 25th day of the billing cycle was $540.
--------------------------------------------------------------------------------------------------------------------------------------------------------
【答案】D
【思路】平均值=
(每天的餘額平均，昨天的期末於今天的期初餘額)，求平均值。已知:1.d1=600，其中dn=-300。且其中無任何金額變動。
(1) 300元是在第21天中付出，所以可得知1~20天每日餘額是600，21~30每日餘額是300即可求總平均值←選項(1)成立
(2)
=540且300是在第25天以前付掉(因期初為600)，第26~30天每日餘額為540( 問題三.300元已在25天錢花掉換句話說26~30的每日餘額不是剩300??) ，即可求總平均值，←選項(2)成立
--------------------------------------------------------------------------------------------------------------------------------------------------------
93.8525-!-item-!-187;#058&006006
If the integer n is greater than 1, is n equal to 2 ?
(1) n has exactly two positive factors.
(2)The difference of any two distinct positive factors of n is odd.
(問題四.我的理解是 N的”任”兩個因數的差是奇數所以B不成立我理解錯了嗎?)
--------------------------------------------------------------------------------------------------------------------------------------------------------
【答案】B
【思路】若兩數相減為奇數，則兩數必為一奇數，一偶數。
兩奇數或兩偶數相減都會是偶數。
(1) n有兩個正因數à只能得知n是個質數。
(2) n = 2 時，兩因數相減的結果有 2 – 1 = 1，2 – (-1) = 3，(-2) – 1 = -3，(-2) - (-1) = -1 四種，全是奇數。
n若n > 2，為偶數：n - 2 會是偶數。
n若n > 2，為奇數：n - 1 會是偶數。
由以上推理可知2是符合條件要求的唯一數字，故條件充分。
感謝戰友們!!
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发表于 2010-7-14 07:39:18
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