Does the question "when did Alice tell you she would go?" ask about the date the plans were talked about or when she plans to go?

Question

Here is the situation:

Alice told Bob on Monday that she would go to the zoo on Friday. Now, if I ask Bob: "Hey Bob, when did Alice tell you she would go to the zoo?"

Will Bob answer Monday or Friday?

If I want to get the other answer, how should I ask Bob?

Answer 1

The question is ambiguous, so Bob could legitimately answer either way.

I think most people would answer "Friday" because this is likely to be the more salient information. But it would depend on the context of your conversation with Bob -- if it's clear that you need to know when he learned when Alice would be going, he'd answer "Monday".

To get a particular answer you can ask:

When will Alice be going to the zoo? -- Friday

When did Alice tell you that she would be going to the zoo? -- Monday