What is the difference between "an answer" and "the answer"?

Question

I've run into one of those cases again where both the definite and indefinite article seem to work. And that makes me very confused as it makes it harder for me to grasp the concept of the articles. Here are some sample sentences that I found on the internet.

At the outset of the interview students were told that if they did not know an answer they could say "pass" and move on to the next question.

It is always a good idea to go over the test to make sure that you answered every question. If you do not know the answer, guess. You may get the right answer or partial credit.

It can be a reasoning exercise in which the student has to figure out an answer on her or his own.

The teacher-librarian serves as a guide to help students figure out the answer on their own.

Are the articles in these sentences interchangeable?

So if you are not talking about any specific answer (you don't know what an answer can be), do you use a or the, or it doesn't matter?

Again, the answer seems to be more common, according to my research, so is it more idiomatic?

Answer 1

If a particular question could have multiple answers, you would use an answer. If a particular question has one answer, you would use the answer.

However, if you have multiple questions (as in your interview example), you have multiple answers (not necessarily per question - each may have exactly one answer or many answers). In this case you would use an answer, since there is more than one answer in the interview (but not necessarily more than one per question).

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To address your examples:

At the outset of the interview students were told that if they did not know an answer they could say "pass" and move on to the next question.

There are multiple questions in an interview. It's possible they will each have only one correct answer; even in that case there are many answers throughout the interview.

It is always a good idea to go over the test to make sure that you answered every question. If you do not know the answer, guess. You may get the right answer or partial credit.

This one, I expect, is contributing to your confusion. Each question on the test has a single answer, but the test has many. The first sentence talks about the test as a whole, where it can be understood that the second and third sentence talk about a particular question (without making the transition very obvious, other than using "the answer" and "the right answer").

It can be a reasoning exercise in which the student has to figure out an answer on her or his own.

It's a reasonable expectation that a reasoning exercise may have multiple correct answers (or no correct answer at all), and that each student will likely come up with something different.

The teacher-librarian serves as a guide to help students figure out the answer on their own.

This likely refers to the general case of a student having a question. The student wants to find the answer to the question (or possibly an answer). For the general case of an unknown/unspecified question, the answer is usually used (at least I would, and that seems to be what I've seen), although an answer would also be correct.

Answer 2

There are two kinds of questions: those with only one right answer (The president of what South American country died a few days ago? "Venezuela" is the answer) and those with more than one (Who played James Bond in the 007 movies? "Sean Connery" is an answer, as is "Roger Moore", as is "Pierce Brosnan", etc.).

Questions that are open-ended, e.g., What is the best way to end the slaughter in Syria's civil war?, also have many answers, but they're all speculative; however, if that's an interview question and you have no answer for it, then it's possible and correct to say If you don't have an answer, say "pass" and move on to the next question.

The quote you give is a bit confusing to me, too, because it doesn't tell the reader what kinds of questions are being asked. If they're all multiple choice, they should all be the answer. If they're all open-ended questions or questions with more than a single answer, they should all be an answer. But so many writers these days don't bother proofreading what they've written to ensure that it says what they want it to say and what they mean to say, and too many don't mean what they say.

Answer 3

As a native speaker I definitely see a difference between using an answer and the answer, but as always it depends on the context.

The main difference is that one suggests an absolute answer, something that is the truth or 'the right' answer. And the other suggests 'an answer' in the sense of just a response.

An answer

This I would interpret more like a response and not necessarily having a grounding in true or false. For example, after a job interview they might say:

Please give us an/your answer by next week.

But they wouldn’t ask for 'the' answer because its not a true/false scenario.

Whereas in a test or exam the examiner would be looking for the answer, meaning the answer that is valid.

He calculated that 32+7 was 52, which wasn't the answer.

Also this can be used to show a desired response.

She said she wouldn't marry him, not the answer he wanted.

This nuance is perhaps a difficult one.

Answer 4

A(n) in this context is used to refer to a random object from a group and it implies there are several to choose from.

The in this context is used to refer to a specific object that is unique, or you want to distinguish it from the rest (making it unique).

For example, you do not refer the following words with a(n) because they are unique:

• The queen of England
• The sun
• The fast Ferrari (because it is fast and a Ferrari)

However if you just want to pick a generic object you use a(n):

• A fish in a pond
• A nice car driving by
• A good hike

Let's break down your example with this knowledge.

They did not know an answer.

The answer is unknown to the students, so an is used because there is no specific one stated.

If you do not know the answer.

Here somebody does know an answer so it is specific, and the is used.

the student has to figure out an answer.

We don't know what the answer of the student will be so we use an.

The teacher-librarian serves as a guide to help students figure out the answer.

The teacher-librarian knows the answer, so you use the because that person knows a specific answer.