Tuesday's Puzzles: December Edition
Three puzzles: Logic (☕☕☕); Geometry (☕☕☕); Probability (☕☕☕☕)
Dear Friend,
I’m so glad to see you here.
Three puzzles, three sips of math: Are you ready for your mid-December brain brew?
For today’s edition, I selected three puzzles from logic, geometry and probability. As usual, you’ll find the estimated difficulty marked with coffee cups ☕, a hint of how many cups you might need to tackle the problem (just a warning, not a recommendation!).
Note:
All puzzles 1 and 2 call for a touch of creativity.
🧩 The Puzzles
Puzzle 1 (Logic) — ☕☕☕
You’re in a room with three switches (A, B, C) that control three bulbs in the next room. You can flip switches any way you want, then go into the other room once to check bulbs. How do you identify which switch controls which bulb?
Hint: Use heat as well as on/off.
Puzzle 2 (Geometry) — ☕☕☕
Folding an A4 piece of paper yields a polygon (a geometrical figure) with N edges. The value of N depends on how you fold it. What are all the possible values for N?
Hint: Take a piece of paper and try it yourself!
Puzzle 3 (Probability) — ☕☕☕☕
100 passengers board a plane with 100 assigned seats.
Passenger 1 has lost their boarding pass and sits in a random seat.
Each subsequent passenger:
Sits in their own assigned seat if it’s available
Otherwise, picks a random empty seat
What is the probability that Passenger 100 (the last to board) ends up in their own assigned seat?
Hint: Don’t try to track all 100 passengers. Instead, ask yourself: Which seats actually “matter” to the final outcome? Think about what conditions would guarantee Passenger 100 gets their seat versus guarantee they don’t, and when those conditions get decided.
🔹 Suggested approach: Try the puzzles in order of difficulty, and, most importantly, have fun!
That’s all for this week’s brew of puzzles! How did you find them: Too easy, too tricky, or just right? I’d love to hear from you!
🗓️ Next week teaser
Next Tuesday, The Cafe will present a freshly brewed selection of AI prompts (my personal favourites).
I look forward to seeing you then.
Until then, have a wonderful week!
With love and curiosity,
Sybille ☕
P.S.: Solutions will appear in next week’s edition of The Café.
In the meantime, paid subscribers are very welcome to share their solving process and tentative answers using this form: I’ll send back personal feedback, tips, and good coffee vibes ☕💡.