Worked examples: passwords, codes, sequential choices — IITM BS previous year questions

Worked examples: passwords, codes, sequential choices is part of Basic Principles of Counting (L5.1), Week 5 in Statistics 1. Prasnya files every IIT Madras BS previous year question from this subtopic here, each one with a worked explanation. Take the whole set as a timed mock and you get accuracy, pacing and per-question analysis back.