A farmer is trying to get her fox, chicken and grain to market, but first they must cross a river. Fortunately, there\u2019s a small rowing boat she can use. The problem is that the farmer can only take ONE thing in the boat at a time. Also, if the fox is left alone with the chicken, then it will eat the chicken. The same is true if the chicken is left with the grain.
\nCan you help the farmer get everyone across the river without anything being eaten?<\/p>\n
Cheryl\u2019s Birthday<\/strong><\/p>\n This problem became famous a few years ago when it was set in the Singapore and Asian School Math Olympiad. It\u2019s actually quite an old question \u2013 I remember tackling it in secondary school. The problem goes like this:<\/p>\n Albert and Bernard have just become friends with Cheryl, and they want to know when her birthday is. Cheryl gives them a list of 10 possible dates:<\/p>\n \u2022 May 15, May 16, May 19 Then, separately, Cheryl tells Albert the month and Bernard the day of her birthday. The boys had this conversation:<\/p>\n Albert<\/strong>: I don\u2019t know when Cheryl\u2019s birthday is, but I know that Bernard doesn\u2019t know either. So when is Cheryl\u2019s birthday?<\/p>\n![\"\"](\"\/studiowebsite\/wp-content\/uploads\/2019\/10\/farmer-fox.png\")
\nThis puzzle was created in the 9th century! Isn\u2019t it amazing to try problems from more than a thousand years ago? Check your answer here<\/a>.<\/p>\n
\n\u2022 June 17, June 18
\n\u2022 July 14, July 16
\n\u2022 August 14, August 15, August 17<\/p>\n
\nBernard<\/strong>: At first I didn\u2019t know when Cheryl\u2019s birthday is, but now I know.
\nAlbert<\/strong>: Then I also know when Cheryl\u2019s birthday is.<\/p>\n
![\"\"](\"\/studiowebsite\/wp-content\/uploads\/2019\/10\/Konigsberg_bridges.png\")
<\/p>\n