We Got A Problem #13: The Birthday Problem

At my son’s recent 5th birthday party, he got 15 birthday cards.  Sure enough, he got more than one of the same card.

Suppose everyone buys their cards at Foyerjohn, and randomly picks one of the cards.  How many different cards would need to be on sale for there to be a 50% chance that all 15 people pick a distinct card?

Harder: how many different cards would need to be on sale for there to be a 50% chance that my son doesn’t get three of the same card?

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Fostering a New Generation of Confident Mathematical Thinkers

EDC’s Matt McLeod has posted some thoughts on teaching and coaching with a focus on mathematical habits of mind.  He describes some parts of an ongoing research study about how teachers’ impressions of mathematics change when teaching from a curriculum that emphasizes these habits.

http://ltd.edc.org/fostering-new-generation-confident-mathematical-thinkers