Secret Santa

santa

The rules of a secret santa are that each person’s name is put in a hat and the names are mixed. Then each person must choose 1 name from the hat. If you choose your own name, you must put it back in the hat.

If 2 people do a secret santa there is only one solution: Person A gives to person B and person B gives to person A.

Stage 1: With 3 people, there are 2 possible ways. Can you think why?

Stage 2: Now how many different ways are there with 4 people?

The final challenge is to find the number of different scenarios with 5 people.

Solutions can be found here.

Galton’s Board

galton board

This week we looked at an online simulation of the Galton board (or Bean Machine), which is a device where beads are dropped from a funnel at the top through ranks of nails.
Each time a bead strikes a nail it has a 50% chance to veer left and a 50% chance to veer right.

Each bead eventually drops in one of the column A, B, C, D or E.

1. Do you think the probabilities for a bead to land in A,B,C,D or E are equal ?
2. If not which column has the highest probability ?
3. Can you do a computer simulation of 10,000 beads dropping in a Galton
board using scratch or Python ?