Lesson 1: From daily users to requests in flight
21 min read·
Module 3 · Lesson 1 · About 45 minutes · Needs: Module 2 lesson 3 (the constraints Joel wrote down), school arithmetic, and enough Python to run a cell. No model calls and no key.
The situation
Week 3 at Northdesk. Joel's target for the second quarter of 2027 sits in TARGET: 100,000 daily Ask users, 10 questions each, 2,000 input and 500 output tokens, a 3-second response, a peak factor of 4. Helen will not look at an architecture until the numbers are on one page. Funmi asks the first question: how many requests arrive in the busiest second, and how many are in progress at once?
This lesson answers with the traffic part of the roadmap's worked estimate; lessons 2, 4 and 5 do tokens, cost and latency.