problem vs question

problem

noun
  • A difficulty that has to be resolved or dealt with. 

  • A puzzling circumstance. 

  • A set of moves required to complete a climb. 

  • A question to be answered, schoolwork exercise. 

  • Objection. 

  • Difficulty in accepting or understanding or refusal to accept or understand. 

adj
  • Causing a problem; problematic; troublesome. 

  • Difficult to train or guide; unruly. 

question

noun
  • A subject or topic for consideration or investigation. 

  • A sentence, phrase or word which asks for information, reply or response; an interrogative. 

  • A proposal to a meeting as a topic for deliberation. 

  • A doubt or challenge about the truth, accuracy, or validity of a matter. 

verb
  • To ask a question or questions; inquire or seek to know; examine. 

  • To ask questions of; to interrogate; to ask for information. 

  • To raise doubts about; have doubts about. 

How often have the words problem and question occurred in a corpus of books? (source: Google Ngram Viewer )