1. 把6升的壶装满水,把水倒在5升的壶里,剩下1升水。把5升壶里的水倒空,把剩下的1升水到近5升的壶里。再把6升的壶装满水,把水倒在5升壶里,剩下2升水。把5升壶里的水倒空,把剩下的2升水到近5升的壶里。再把6升的壶装满水,把水倒在5升壶里,就剩下3升水。 2. 盛满水的三个瓶子是a1,a2,a3,三个空的是b1,b2,b3,6个瓶子的顺序是a1,a2,a3,b1,b2,b3。把a2拿起来,把水倒在b2里在放回原处,就行了 7. 竖着摆 8. 方块5 |
【9】 A B C 36 108 144 |
4. This is probably the most difficult one in the group. I do not know why it is a psych problem. I think it is purely a math problem. An envy-free solution for 3 people case was given by the Selfridge-Conway discrete procedure gives a envy free division for three players.
The cake minus the trimmings has now been divided in an envy free manner. Call the second or third player who received the trimmed piece A and the other one B.
The reasoning behind the algorithm is tricky and a good exercise for the reader! The important point to note in a proof is that the first player will not be envious of A even if A gets all the trimmings. (quoted from wiki.) 5. Suppose the radius of a coin is 1, the condition that any extra coin will have contact with at least one existing coin implies that for any point on the table surface, there is at least one center of an existing coin within distance 2. In other words, if we have bigger coins with radius all equal to 2, then these enlarged coins at exactly the same centers should fully cover the rectangular table surface. Equivallently, if we shrink the rectangular table's width and length both by 1/2, then obviously the shrinked surface would be able to be covered by the original radius 1 coins. But we just proved that those n coins can cover 1 of the 4 parts of the table surface if we cut the table surface from its center with two lines parallel to the two sides respectively. Therefore, 4n coins can cover the entire surface, given each n-group can do their parts.
6. I was just thinking putting it against a wall will do the trick, but I am not sure whether that is allowed.
7. I do not think even 4 coins on the same plane can touch each other at the same time. But obviously 3 coins can. Put one coin flat down at the bottom, 3 coins flat on top of it and touching each other. The last one stand vertically in the center, that should work.
And finally, btw, #10 is a good problem again to remind many people not to take numbers for granted :) |
unique radius-thickness ratio to work. Apparently not possible. How about this way then? two coins #1, #2 in the same plane A tangent to each other. The third coin #3 stays in a plane B that is perpendicular to plane A, and tangent to #1,2. now It is possible to put one coin on each side of plane A that touchs #1,2,3 slantly. And coin #4 and 5 will touch each other undergoing the bottom of #1,2. I do not know how to do picture here.... I tried with some nickles, seems like ok ... |
您的方法看来仍有问题,因为#4和#5被#1 和#2 挡着,难以同时触及#3。 94哥哥可以试试这样做: #1平放在桌面上,在它上面标一条直径AB。#2垂直(于桌面)立于#1边上A点,它的平面通过AB。垂直立#3和#4于#1上,它们的触点在#1的圆心O和B点的连线(#1的过B点的半径)上很靠近O点的地方的上方(高为半径),使得#2恰是#3和#4的角平分面。这时#1、2、3、4已符合要求。在OB上取一点D,把#5的边放在D上,保持#5与#2垂直,让#5斜靠在#3、4(或在#2)上。调整D点在OB上的位置及#3和#4的夹角,使得#5与#3、2、4都接触。 |
1。 a: 5L的壶 b:6L的壶 第一步,b灌满水,用b里的水倒满a. 然后把a里水倒掉,把b里剩下的1L水倒入a 第二步,b灌满水,用b里的水倒满a, 然后把a里水到掉,把b里剩下的2L水倒入a 第三步,。。。。。。。。。。。。,于是b里还剩3L水 2。 把第2只杯子里的水倒入第5只杯子 3。小李如果先打小黄,小黄若死,小李必死。小黄不死,他这枪岂不是废了。所以他肯定打小林。 所以小黄也接着打小林,原因一样。这样第一轮小林被小李打死的概率为30%,被小黄打死的概率为35%, 共65%。 一:若小林活到最后,那么肯定先打小黄再打小李,所以小林活到最后的概率为(1-65%)×70%= 24。5% 二:再来算小黄的。小黄活到最后的条件是:第一轮小林被打死,最后小黄把小李打死。小黄把小李打死分 为两种情况: 第一,小李第一枪就干掉了小林(概率30%),然后小黄先打小李中了(50%),或者没中 然后小李也没中,直到最后干掉小李。第二,小李第一枪空,然后小黄干掉小林(35%),接着小李先开枪 不中,小黄再开枪直到杀死小李。所以第一中情况的概率为30%×(50% + 50%×70%×50% + 50%×70%×50%×70%×50%+……),第二种概率为35%×(70%×50% + 70%×50%×70% ×50%+……),都是等比数列可以算出结果,加起来就是小黄存活的概率。于是最后小李存活的概率也 出来了。 99%的可能做错了,但是我已经处在崩溃边缘,后面的题今天也不想思考了,最后一道题论坛里有,基础概率的问题。 |
在#1上标出相互垂直的两条直径AB和CD,将其放在桌面边上,让D点伸出桌面少许。置#2和#3于同一垂直于#1的平面上并分别立于#1边上的A点和B点,它们有一个接触点E(在#1的圆心上方,高度为硬币半径)。于C点斜立#4,使其靠在#2和#3上,接触点分别为F和G。这时硬币#1、2、3、4已符合要求。最后,将#5的一面贴在D点,使其周边触及E点,然后在保持其一面贴在D点且与#2及#3不脱离(触点H和I必分别在弧EF和EG上)的情况下上移,直至其周边触及#4的一面于J点。这样,从A到J,共有C(5,2)=10 个触点为5个硬币分享。 |
6升倒进5升,6升内留1升,把5升倒空,1升倒进5升内,再次取满6升,倒进5升,6升内留有2升,倒空5升放入2升,再次取6升倒入5升,6生内就有3升水了. |
第一個問題:先把6升的空水壺裝滿水,然後倒出一半的水出來,剩下的就是3升水了. |
4. 在A, B, C三犯人中,由A分汤。由B给A选一碗汤;随后由C在剩下的两碗汤中给B选一碗, 另一碗给C自己。 |
1-1 6表示6升桶,5表示5升桶.操作方法6倒5余1,清5,余1倒入5,6接满倒入5余2,清5,余2倒入5,6接满倒入5余3 1-【2】:将第二杯里的水倒入第二个空杯 1-3:小李先开枪,小黄第二,小林最后 都先打小林 1-4:第一个人把汤分成三份,第二个人选择二份;第三个人有权决定由自己重新分配或接受第二个人的分配两份中选择一份给自己 1-7:底下摆三 上面俩个摆在下面三个硬币之间的两个空上 ----- 就这样 1-8:黑桃4 |
7)那底下的两头那两个并没有接触啊。 |
1) 6升水壶的水 pour into a 5升的水壶; 6升水壶的水 there remains 1升水; pull in to empted 5升的水壶 6升水壶的水 pull in 有 1升水 的5升水壶; 6升水壶的水 remain 2升水 pull in to empted 5升的水壶 6升水壶的水 pull in 有 2升水 的5升水壶; 6升水壶的水 remain 有3升水
2) 前面 second 盛满水的杯子 pour in 后面 second 空的杯子.
3) 小李先开枪(命中率是30%) shoot 小林 (because 小林比小黄命中率好) 小黄 (命中率50%) rather 开枪 shoot 小林 (because 小林比小李命中率好) 小林 (命中率100%) rather 开枪shoot 小黄 (because 小黄比小李命中率好) Now 小李 once again has a 30% chance of killing 小林 Therefore, at this point 这三个人中小李活下来的机会最大 because no one wants to shoot him yet and 小黄 has a 100% chance of dying , while 小林 already had three different chances (30% , 50% , and 30% chance of dying.)
4) Let 三个人 = A,B,C A 分汤; B 选一罐汤 to A; remaining are 两罐汤让 C 先选, B took the last one.
5) ??? 6) ??? 7) ?
8) When P先生 said:我不知道这张牌; then 这张牌的点数 must be an Ace, a Queen, a 4, or a 5 . When Q先生 said:我知道你不知道这张牌; then 这张牌的花色 must be one of the four suits. Then P先生 said:现在我知道这张牌了。 ??? How ???
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有趣的逻辑思维测试题(一)
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小李的策略应该是第一枪故意放空。 这样: 小李活下来的概率是 45% 小黄活下来的概率是:20% 小林活下来的概率是:35% 小黄可怜,尽管枪法不错,活下来的概率却最小。 另一点,枪法并不是最重要的,策略最重要。 |
比我聪明! |
第二题:将中间满瓶的拿起来将水倒进中间空瓶的杯子 |
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