The site, at the time this answer was written, has 90,000 questions give or take.  
  
The answered rate is 75%.  
  
So the inverse is actually true.  

1 in 4 questions is unanswered or abandoned.
That's quite the opposite of 1 in 20 answered.  
  
[Reference][1]
[1]:https://stackexchange.com/sites#