Step 1: Analyze statements —
All Mathematicians are Statisticians → Mathematicians ⊆ Statisticians.
Some Statisticians are Computer Scientists.
No Computer Scientist is a Mathematician → Mathematicians ∩ Computer Scientists = ∅.
Step 2: Evaluate conclusions —
I. Some Statisticians are not Mathematicians → True, because some Statisticians are Computer Scientists, who are not Mathematicians.
II. All Statisticians are Computer Scientists → Not necessarily true.
III. Some Mathematicians are Computer Scientists → False, no Mathematician is a Computer Scientist.
Step 3: Conclusion — Only I necessarily follows.