Well, the stuff wasn’t entirely irrelevant. One of the positions was a currency related stuff, so understanding the Yen bit was relevant. Turned out the guy who asked me didn’t know either but wanted hear me think through the issues and come up with an analysis. The log transformation question was relevant because there were quantitative aspects to the job. And there was climate related stuff on my resume that they chose to dig into. So it wasn’t completely random.
Usually they’re trying to dig into how you think, rather than whether the answer is right. I’ve heard that people have been asked things like “estimate the number of light bulbs in Manhattan,” clearly getting the right answer is not the key issue here, but watching how you handle coming up with estimates of things for which you have very incomplete information, which is actually a pretty important skill for investors to have.
And by the way, the people I interviewed (except maybe one) were all very nice. They just asked tough questions, but it wasn’t as if they acted all superior about it.