It's a bit rude but until senior-level-role-interviewing candidates can stop falling over on the basic questions why waste time with harder ones? The "candidate

It's a bit rude but until senior-level-role-interviewing candidates can stop falling over on the basic questions why waste time with harder ones? The "candidate with an MS degree in CS and x years at SomeCo, can't do FizzBuzz" isn't a myth, it really happens to people giving interviews. I've been having to give some interviews lately (though unfortunately they have to be within 'process') and my basic question is to write some code (with a computer) that outputs the endpoints of a line segment which bisects a plane between two input control points. (I give all the equations needed and the code is done within an application already set up.) It's still managed to trip up some people with experience who seemingly don't have the concept of representing a line mathematically (BS or MS in Physics, how?). We also tested it on intern candidates under shorter time constraints and a couple internal people, they did much better, I think all but one actually got the basic line done within half an hour even if edge cases remained. If we're given longer time constraints the problem and application framework scales to more interesting subjects like generating n-point voronoi diagrams and their applications, but we haven't gotten there with anyone yet...