Design Bayesian Network models for a set of exercises in the Numbers and Relations domain

Unlike most other projects, this one does not require you to program. Instead, you will need to create probabilistic models of learning exercises in the math domain of Numbers and Relations. 
A typical task in this domain would look like this:

“Imagine Matryoshka dolls that fit into each other, due to a decreasing height. The biggest doll is 32 cm high. Each next doll is 25% smaller than the previous one. In this sequence, there are no dolls smaller than 6 cm.
How many dolls are there in this series?
Write down your intermediate steps.“

The tasks and solution strategies (with step-by-step application of intermediate steps) will be provided.
The objective of the project is to design a Bayesian Network (BN) model of each task that would help diagnose skills responsible for incorrect solution.

The free tools GeNie (or any other) can be used to design BN models.

[1] GeNie tool: https://www.bayesfusion.com/
[2] Cristina Conati, Abigail Gertner, Kurt VanLehn. Using Bayesian Networks to Manage Uncertainty in Student Modeling. User Modeling and User-Adapted Interaction November 2002, Volume 12, Issue 4, pp 371–417. https://pdfs.semanticscholar.org/15a0/17a67d5490a9c28db0773fe2a8fcfaf3a1dc.pdf