How do you show which of these is the smallest (the question in mind is related to variance but its not relevant here, I just dont know how to compute the fractions, but in case it makes it any easier, m & n are samples).

1. o*/n

2. [(o*/n)/2] + [(o*/m)/2]

3. o*/m+n

3 is obviously smaller than 1 but I dont know which is smaller out of 2 & 3, and I need to prove it.

Any help would be much appreciated. Thanks