prototype function not working?

/*You should consider creating an object that can be considered as a single entity. Instead of questions, maybe question. If you want a collection of questions, then create an array of those objects... This makes things a little easier to reason about as well as manipulate. Moreover, consider choosing meaningful and different names for objects, function parameters, and properties or functions associated with an object.*/

function questions(questions){
  this.questions = questions;
}
/*The naming conventions here are not incorrect and this will work if you are just trying to create a question object. However, the array of questions inside of an object makes things difficult to reason about.*/

questions.prototype.addquestion = function(){
  var questions = [];
  var ask = questions.push(this.questions); 
/*the push method of arrays returns the new length of the array after the added element*/
  for(i=0; i<ask; i++){
    console.log(ask[0]); //This will be an undefined quantity because of ask does not contain a collection type
  }
}

questionone = new questions("question one");
questionone.addquestion();

//Define a question object prototype through a constructor function
function Question(text, answer){
      this.text = text;
      this.answer = answer;
}

//Create a QuestionBank object that encapsulates the behavior of the array that is storing your question objects
function QuestionBank(){
    this.questions = []; //A question bank is an empty collection upon creation.
} 

QuestionBank.prototype.addQuestion = function(question){
      this.questions.push(question); //Adds the question to the question bank
}

//Print all of the questions in the question bank
QuestionBank.prototype.printBank = function(){
   for(var i = 0; i < this.questions.length; i++){
        console.log("Question " + i +": "+ this.questions[i].text + "\n");
    }
}

/*How would you use this?*/

var q1 = new Question("What is your favorite color?", "Blue");
var qBank = new QuestionBank();
qBank.addQuestion(q1);
qBank.printBank();