Do I know in advance whether a bonus to attack roll will help hit?

Question

Adept's Insight says:

Noble Adept Feature Adept's Insight
With a mental focus, you enhance the undeniability of your actions.
Encounter        Psionic
Free Action      Close burst 5
Trigger: You or an ally in the burst makes an attack roll, saving throw, or skill check.
Effect: You add 1 to the triggering roll.
Augment 1
Effect: You instead add 1d4+1 to the triggering roll.

I want to apply it to an attack roll, but only if +1 (or +2, if augmented) would actually help me to overcome the monster's defense. Do I know if the +1 (or +2) bonus would be enough to hit the monster, i.e. can I ask the DM to tell me?

Normally, we announce our attack roll+modifier and the DM says "it hits" or "it misses," and vice versa, the DM announces monsters' attack rolls and we say whether it hits our characters.

Answer 1

You know the result of the roll, whether or not you know the outcome depends on the type of roll.

If it's a saving throw, you likely know the outcome since you only need a 10. However if it's an attack roll or skill check, you know your total, but you don't know the target's defense or the check's DC so you don't know the result (unless of course you have knowledge already acquired on a previous turn or whatever). This isn't an absolute of course the DM can reveal whether it's a hit or miss, success or failure, but the power does not provide for learning that prior to deciding.

This is a free action which is triggered. The rules for triggered actions that are not interrupts or reactions is that they happen after the trigger completes unless that doesn't make sense (like in this case they happen after the roll, but before the damage roll on an attack).