Calculating percentage from two tables

I have two tables:

• First one contains unique mentees under one mentor, so mentors can have more than one mentee in that table.


• Second one contains interactions of mentors with mentees on different dates, so mentos and mentees may appear multiple times.

I'm trying to create a join between those two tables where the result would be:

'mentor_id'|'# of people'|'# of distinct interactions'  

This way I would know whom did the mentor advice during a given period, against how many they are supposed to as %.

What I've done..

SELECT INTER.mentor_id, COUNT(DISTINCT INTER.mentee_id), COUNT(f.mentee_id)
FROM INTER WITH (NOLOCK)
INNER JOIN  
    (SELECT mt.mentee_id, mt.mentor_id
     FROM mentee_table mt WITH (NOLOCK)
    ) as f 
ON f.mentor_id = INTER.mentor_id
WHERE (//period)
GROUP BY INTER.mentor_id

The problem with this is that when viewing the result without any groupings or aggregates, I can duplicates from the the subquery, since there are more records in TRANS.

Schema's

mentee_table

|mentee_id|mentor_id
|1        |3
|2        |3
|3        |5

TRANS

|mentee_id|mentor_id
|1        |3
|1        |3
|1        |3
|2        |3
|3        |5
|3        |5

In the end I will just use the counts to calculate percentage, such as

COUNT(DISTINCT INTER.mentee_id)*100/COUNT(f.mentee_id) which means the INTER table, when distinct, can only have <= # of people

Thanks