Suppose you are sitting in an interview and the interviewee asks you an aptitude question.
You have three buckets with capacity 4 liters, 8 liters and 10 liters and you have a large tank of water. Now you have to measure 3 liters of water precisely using those buckets. How will you do it?
It is impossible. The reason is that we are asked to measure 3 liters which is an odd number but the buckets we have can contain even liters of water only (4, 8 and 10). If you hoped to fill any of the bucket half, you will not be precise in measurement.