Probability help.

I think that you need to tell us what the question is

That is the question.

In a bank there are 3 safes each with 2 drawers. The first safe has 2 drawers alarmed, the 2nd has 1 drawer alarmed and the 3rd has none. A burglar comes:

i)Prob. burglar sets off alarm.
ii)Given that the alarm didn't go off, what is the prob. the other drawer is alarmed.

Is this in the same safe, or in any safe? If it's in any safe, then just look at how many unopened drawers there are, and how many are alarmed and how many aren't.

The other would suggest the same safe.

tbh that was the bit I was unsure of but, if the question does not say that he opens 2 of the same safe then there is a lack of clarity

does it even say that he opens 2 drawers?

The other would suggest the same safe.

Then in that case it would be 0.5 I guess. He can't have opened the safe with two alarmed drawers. If he opened the safe with one alarmed drawer, and opened the non-alarmed drawer, the other one would be alarmed. If he opened the safe with no alarmed drawers, the other one wouldn't be alarmed. So there are only two possible outcomes, of equal likelihood.

The question sounds extremely unclear. Either you're not posting the entire question, or it's a very poorly written one. Is it from a textbook, or a past exam paper or what?

The question is fine.

The question is fine.

Given that you found it confusing and we all consider it to be poorly written, surely it is not fine

But if it simply means that he opens an unalarmed drawer, what is the probability that the other drawer in that safe is unalarmed then, as has been said, the answer is just 0.5