"[quote="thunderbeast"]its either 2 or a variable seeing hat the answer is not given but a question mark has taken its place the question mark is (in this case) A variable so it can be any number ..."
You are wrong. I have put this puzzle online, so, I know the answer and the answer is not longer than 1 decimal place. So, You can't say that answer is "Pi" or something like that.
Answer is a number x, 0 < X < 7. X≠pi. 0 < 4 < X <7