Hubwoo.com Analyst interview questions

My final (8th) interview ended with a brain puzzle. It was about three buckets one with apples, one with oranges, and one mixed. All three buckets had a label: apple, oranges, mixed, but the labels were wrong. How many times do you have to blindly reach into bucket and pull out it's contents to know what's in each bucket? (this is rare, I don't imagine this kind of questions is common)