How many persons are standing exactly between Y and Z ?

X is at one of the ends. J is fourth to the right of X.

Now this presents 2 scenarios, one where X is facing north and the other where X is facing south.

Considering the scenario where X is facing North :-

Each of the neighbors of J are facing North.
Now J can be facing either north or south. Lets first consider the case when J is facing north.
Now M is facing in the same direction as J and is standing third to the right of J. L is one place away from M. L is also at the third position from the right of Y, thus :-

Now Z has to stand to the immediate left of L, hence this case is rejected.


Now lets consider the case where J is facing south :-
Again M is facing in the same direction as J and is standing third to the right of J. L is one place away from M. L is also at the third position from the right of Y. Also Z is standing to the immediate left of L. Thus :-

Now since K is neither facing north, nor standing at the end, this case too is rejected.


Considering the case where X is facing south :-

Again J can either face North or South.
Considering the case when J is facing North :-
M is facing in the same direction as J and is standing third to the right of J. L is one place away from M.

In this case, Z can't stand to the left of L. Hence, this case is rejected.


The only remaining possibility is that J is facing South.
Following all the conditions, the final arrangement looks like :-

3 people are standing between Y and Z.