Here is a mathematical problem which did the rounds on Twitter and other social media a couple of weeks ago. Everyone thought it was too difficult for learners to understand, and this was presented at the Grade 8 level in Singapore (one of the world’s best countries for mathematical learner proficiency, where South Africa is in last place).
The question is simple “When is Cheryl’s birthday”.
See if you can work this out for yourself, and I can assure you that there IS enough information given.
Over the next few days I will provide hints until we arrive at the answer.
The Problem : When is Cheryl’s birthday
Albert and Bernard just became friends with Cheryl, and they want to know when her birthday is. Cheryl gives them a list of 10 possible dates.
May 15 May 16 May 19 June 17 June 18 July 14 July 16 August 14 August 15 August 17
Cheryl then tells Albert and Bernard separately the month and the day of her birthday respectively.
Albert: I don’t know when Cheryl’s birthday is, but I know that Bernard does not know too.
Bernard: At first I don’t know when Cheryl’s birthday is, but I know now.
Albert: Then I also know when Cheryl’s birthday is.
So when is Cheryl’s birthday?
When you have read this, then try to work this out for yourself, and if you need help then move onto the First Hint.