tt-2-23,2-13

allen0018 · 发表于 2006-7-21 15:55:00

Q23:

AMOUNT OF BACTERIA PRESENT

Time

Amount

1:00 P.M.

10.0 grams

4:00 P.M.

x grams

7:00 P.M.

14.4 grams

Data for a certain biology experiment are given in the table above. If the amount of bacteria present increased by the same fraction during each of the two 3-hour periods shown, how many grams of bacteria were present at 4:00 P.M.?

A. 12.0

B. 12.1

C. 12.2

D. 12.3

E. 12.4

by the same fraction 什么意思？

Q13: 理论上的证明。

An integer greater than 1 that is not prime is called composite. If the two-digit integer n is greater than 20, is n composite?

(1) The tens digit of n is a factor of the units digit of n.

(2) The tens digit of n is 2.

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

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

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

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

不要猜数，谁能帮我证明一下？？？

谢谢阿

Q13: 理论上的证明。

An integer greater than 1 that is not prime is called composite. If the two-digit integer n is greater than 20, is n composite?

(1) The tens digit of n is a factor of the units digit of n.

(2) The tens digit of n is 2.

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

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

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

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

不要猜数，谁能帮我证明一下？？？

谢谢阿

Q13: 理论上的证明。

An integer greater than 1 that is not prime is called composite. If the two-digit integer n is greater than 20, is n composite?

(1) The tens digit of n is a factor of the units digit of n.

(2) The tens digit of n is 2.

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

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

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

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

不要猜数，谁能帮我证明一下？？？

谢谢阿

silviaqiu · 发表于 2006-7-21 16:07:00

第一题:by the same faction就是以同样的倍数或比率

第二题:假设十位数是m，个位数是km，且k和m都是positive　intergers，那么这个数字n可以表示为10*m+km，if n is divided by m, that is to say, n/m=(10*m+km)/m=10+k＝一个interger,又由已知可得，m＞１，那么根据合数的定义就是，除了１和它自己本身，有其他的因数，那么这个n除了１和自己本身，还有一个大于１的因数m，所以说这个n一定是一个合数．

顾风 · 发表于 2006-7-21 16:17:00

以下是引用allen0018在2006-7-21 15:55:00的发言：

Q23:

AMOUNT OF BACTERIA PRESENT

Time

Amount

1:00 P.M.

10.0 grams

4:00 P.M.

x grams

7:00 P.M.

14.4 grams

Data for a certain biology experiment are given in the table above. If the amount of bacteria present increased by the same fraction during each of the two 3-hour periods shown, how many grams of bacteria were present at 4:00 P.M.?

A. 12.0

B. 12.1

C. 12.2

D. 12.3

E. 12.4

by the same fraction 什么意思？

Q13: 理论上的证明。

An integer greater than 1 that is not prime is called composite. If the two-digit integer n is greater than 20, is n composite?

(1) The tens digit of n is a factor of the units digit of n.

(2) The tens digit of n is 2.

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

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

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

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

不要猜数，谁能帮我证明一下？？？

谢谢阿

Q13: 理论上的证明。

An integer greater than 1 that is not prime is called composite. If the two-digit integer n is greater than 20, is n composite?

(1) The tens digit of n is a factor of the units digit of n.

(2) The tens digit of n is 2.

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

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

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

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

不要猜数，谁能帮我证明一下？？？

谢谢阿

Q13: 理论上的证明。

An integer greater than 1 that is not prime is called composite. If the two-digit integer n is greater than 20, is n composite?

(1) The tens digit of n is a factor of the units digit of n.

(2) The tens digit of n is 2.

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

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

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

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

不要猜数，谁能帮我证明一下？？？

谢谢阿

13题，先看第一个条件，因为说明了>20，能是因素的有哪几个呢？ 2,3,4。对吧？如果是2，则该数一定是个even,如果是3,一定能被3带除，如果是4，一定是偶数，所以(1)是满足的。而(2)单独并不能满足。所以答案是A

silviaqiu · 发表于 2006-7-21 16:41:00

我还是觉得我的证明比较严谨

顾风 · 发表于 2006-7-21 16:53:00

同意。。。

silviaqiu · 发表于 2006-7-22 01:07:00

帮忙顶一下,lz好看到

allen0018 · 发表于 2006-7-22 17:45:00

thanx,十分谢谢帮忙

敬礼！！！

christlulu · 发表于 2006-10-27 17:38:00

其实13题十位数的数字是个位数的数字的因素，那么这个数字应该就能被十位数的数字正出，那么应该就是合数呀，是不是呀？

dlmmdajgal · 发表于 2008-3-7 06:00:00

The tens digit of n is a factor of the units digit of n.

What does it mean?? like 24, 2 is a factor of 4? what about 30 then? 3 is a factor of 0???

tt-2-23,2-13

tt-2-23,2-13

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