If you are certain they heard you, they are showing very little regard for you by being rude. They are almost as rude as someone that responded to your question.
Take your pick.
They think you're being rhetorical
They didn't hear you
They think you were talking to someone else
They've got their mouth full.
They don't like you
They don't like the question.
They'd rather say nothing than lie.
They haven't the time.
They did speak back but you never heard them.
They can't speak back because they're dumb
They gave up speaking for lent.
Their tongue is tired
You forgot your glasses and were talking to a statue.
They forgot their glasses and think you are a public address system.
The answer is 42 and a half but they don't think you've earned the answer.
Sometimes the search is more valuable than the solution so they are helping your personal development.
You shouldn't have answered. That way you'd have been enigmatic. There's another motive :)
Wow. This is exactly what I was gonna write. Except that I was gonna mention that they might just be rude, snooty, or not speak the language. :)
Awwe Vessa I'm sorry. If I get BA I'll share it with you :)
It's just rudeness ain't it!
Either they didn't hear you, or they don't want to hear you.
Uze your HEAD honey, watta u THINK it meanz
They might be deaf