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wiki:donuts:winter2015 [2015/02/25 13:51]
jmb438
wiki:donuts:winter2015 [2015/04/15 14:22] (current)
jmb438
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 ===== Ants on a log ===== ===== Ants on a log =====
  
-There is a 100m long log. On this log, there are 1000 ants randomly ​places. The ants all travel at 1m/s either left or right, but their direction is random. If two ants touch, they will both change their direction. What is the average time before all of the ants walk off the end of the log? ((Wu Yifeng, Feb 25))+There is a 100m long log. On this log, there are 1000 ants randomly ​placed. The ants all travel at 1m/s either left or right, but their direction is random. If two ants touch, they will both change their direction. What is the average time before all of the ants walk off the end of the log? ((Wu Yifeng, Feb 25))
  
 [[wiki:​donuts:​winter2015:​antsonalog:​answer|answer]] ​ [[wiki:​donuts:​winter2015:​antsonalog:​answer|answer]] ​
 +
 +===== Breakfast =====
 +
 +Two fathers and two sons are eating breakfast. They eat a total of three eggs, but each person eats one egg. How can this be? ((Dr. Warnick, Mar 4))
 +
 +[[wiki:​donuts:​winter2015:​breakfast:​answer|answer]] ​
 +
 +===== Dots and Lines =====
 +
 +How can you arrange 9 dots so that you can draw 10 lines that each touch at least three dots? The lines can cross, but two lines cannot be on top of each other. ((Junming Diao, Mar 11))
 +
 +[[wiki:​donuts:​winter2015:​dotsandlines:​answer|answer]] ​
 +
 +===== Password =====
 +
 +A man worked for a high-security institution,​ and one day he went in to work only to find that he could not log in to his computer terminal. His password wouldn'​t work. Then he remembered that the passwords are reset every month for security purposes. So he went to his boss and they had this conversation:​
 +Man-"​Hey boss, my password is out of date."
 +Boss-"​Yes,​ that's right. The password is different, but if you listen carefully you should be able to figure out the new one: It has the same amount of letters as your old password, but only four of the letters are the same."
 +Man: "​Thanks boss."
 +With that, he went and correctly logged into his station. ​
 +What was the new password?
 + ​((Josh Sypherd , Mar 18))
 +
 +[[wiki:​donuts:​winter2015:​password:​answer|answer]] ​
 +
 +===== Bricks =====
 +
 + A man is being interviewed for a construction job. The boss brings him out to the construction site where they are building a large brick building. To test the man's cleverness, the boss hands him a ruler a asks the man to tell him the length of the diagonal of the bricks they are using. Using only the bricks laying on the ground and his ruler, how can the man find the length of the diagonal of a brick without using any calculations?​ (The diagonal of the brick is shown in red)((Jay Brady, Mar 25))
 +
 +{{:​wiki:​donuts:​winter2015:​brick.png?​200|}} ​
 +
 +[[wiki:​donuts:​winter2015:​bricks:​answer|answer]] ​
 +
 +===== Bridge =====
 +
 +Repeat quetion. See [[wiki:​donuts:​springsummer2013#​the_bridge_crossing|The Bridge Crossing]] ((Mitch Burnett, Apr 1))
 +
 +===== Diophantus =====
 +
 +The Greek Diophantus is sometimes called the father of algebra. A puzzle was written about him by Metrodorus: ​
 +
 +'Here lies Diophantus,'​ the wonder behold.
 +Through art algebraic, the stone tells how old:
 +'God gave him his boyhood one-sixth of his life,
 +One twelfth more as youth while whiskers grew rife;
 +And then yet one-seventh ere marriage begun;
 +In five years there came a bouncing new son.
 +Alas, the dear child of master and sage
 +After attaining half the measure of his father'​s life chill fate took him. After consoling his fate by the science of numbers for four years, he ended his life.' [[http://​en.wikipedia.org/​wiki/​Diophantus#​Biography|W]]
 +
 +How old was Diophantus when he died? ((Dr. W, Apr 8))
 +
 +[[wiki:​donuts:​winter2015:<​title>:​answer|answer]] ​
 +
 +===== One Family, One Boy =====
 +
 +Suppose a group of Chinese families try to change the usual "one family, one child" policy. The want to make it so that each family has one boy. Under the new policy, if the first child is a boy, that will be the family'​s only child. If they have a girl first, they can have another child. If the second child is a boy, they can not have any more children. This way, each family will continue having children until they get a boy, then they must have no more children. If this new policy is put in place, what will be the distribution of boys and girls in China after many years? ((Junming Dio, Apr 15))
 +
 +[[wiki:​donuts:​winter2015:​oneboy:​answer|answer]] ​
  
 /** /**
Line 42: Line 101:
  
 ===== Questions Asked ===== ===== Questions Asked =====
-| Junming Diao | +| Junming Diao | 
-| Jay Brady | +| Jay Brady | 
-| Josh Sypherd | |+| Josh Sypherd | |
 | Dr. Jeffs | 0 | | Dr. Jeffs | 0 |
 | Richard Black | 1 | | Richard Black | 1 |
-| Dr. Warnick ​ | |+| Dr. Warnick ​ | |
 | Wu Yifeng | 1 | | Wu Yifeng | 1 |
-| Mitchell Burnett | |+| Mitchell Burnett | |
wiki/donuts/winter2015.1424897511.txt.gz · Last modified: 2015/02/25 13:51 by jmb438