Seven persons, E, F, G, H, X, Y and Z, are sitting in a row facing north. Only two persons are sitting to the left of G. Only three persons are sitting between G and X. Only one person is sitting between X and Z. E is sitting immediate left of H. Y is not the immediate neighbour of X. How many persons are sitting to the right of F?

Let positions be $1$ to $7$ from left to right (all are facing north).
Step 1: Position of G

Only two persons are sitting to the left of G.

So, G is at position $3$.

Positions:
1 | 2 | 3(G) | 4 | 5 | 6 | 7

Step 2: Position of X

Only three persons are sitting between G and X.

So distance between G and X is $4$.

$3 + 4 = 7$

Thus, X is at position $7$.

Positions:
1 | 2 | G | 4 | 5 | 6 | 7(X)

Step 3: Position of Z

Only one person is sitting between X and Z.

So Z must be at position $5$.

Positions:
1 | 2 | G | 4 | 5(Z) | 6 | X

Step 4: Position of E and H

E is immediate left of H.

Possible empty pairs:

• (1,2)
• (4,5) → not possible because Z is at 5
• (6,7) → not possible because X is at 7

So E and H occupy positions 1 and 2.

Positions:
1(E) | 2(H) | G | 4 | Z | 6 | X

Step 5: Position of Y

Y is not the immediate neighbour of X.

Neighbour of X (position 7) is position 6.

So Y cannot be at 6.

Thus Y must be at position 4.

Positions:
E | H | G | Y | Z | 6 | X

Step 6: Position of F

The only remaining position is 6.

So F is at position 6.

Positions:
E | H | G | Y | Z | F | X

Persons to the right of F = only X

So, one person is sitting to the right of F.