Your key metric is average order value, and it has a very heavy right tail: a few percent of customers bring in half the revenue. How would you build a confidence interval for the difference in means between two groups?
~4 min by voice
How to approach it
They're checking whether you understand that with a heavy tail the standard tools (the t-interval, the bootstrap) become unreliable. They also look at whether you see that every "stabilizing" trick changes the quantity being estimated, and whether you can validate a method empirically.
The interviewer will ask this question and listen. Think out loud and ask for a hint if you need one. When you're done, pause or tap “That's my answer”. In about a minute, your score and the points you covered show up here.