Step 1: Definition of mode.
The mode is the value that appears most frequently in the data set.
Step 2: Count frequencies.
- 35 → 2 times
- 40 → 3 times
- 50 → 5 times
- 60 → 1 time
- 65 → 2 times
- 70 → 2 times
- 72 → 1 time
- 75 → 2 times
- 78 → 2 times
Step 3: Highest frequency.
The value 50 occurs 5 times, which is the highest frequency.
Final Answer:
\[
\boxed{50}
\]