A proportionality puzzle: If half of $5$ is $3$, then what's one-third of $10$? My professor gave us this problem.

In a foreign country, half of 5 is 3. Based on that same proportion, what's one-third of 10?

I removed my try because it's wrong.

Since 5/2 is 2.5, the convention clearly is to round up. Thus, 10/3, being 3.33..., rounds to 4.
