Oh I’m sorry Amy. Yes, I mean 2/3
Now talking about “2/3 of the oranges”, I think there are 2 ways of understanding:

2/3 of the oranges are rotten (we are talking about a certain number of oranges - for example 9 oranges, and 6 of them are rotten)

2/3 of the oranges is rotten (we are talking about one orange of which 2/3 is rotten.

What do you think?

As for:

20 per cent of the students here are female => OK

What about this, Amy:
1 per cent of the students here (be) female.
=> we say one percent, but the number of female students may be greater than one, so…)

Another question has arisen in my mind:
Is it all right to use “one orange of which 2/3 is rotten”? (I know “one orange, 2/3 of which is rotten” is quite correct - just like “she has 3 sisters, two of whom are married”, but I’m not sure whether “one orange of which 2/3 is rotten” is correct or not - and I have no idea why I used it the other day :lol: )