Seven children A, B, C, D, E, F and G are standing in a line G is to the right of D and to the left of B. A is on the right of C. A and D have one child between them. E and B have two children between them. D and F have two children between them.

Who is on the extreme right?

F

G is to the right of D and to the left of B,

=> _, _, _, D, G, B, _

A is on the right of C. A and D have one child between them,

=> C, A, _, D, G, B, _

E and B have two children between them,

=> C, A, E , D, G, B, _

D and F have two children between them,

=>(left)     C, A, E , D, G, B, F     (right)

Thus, "F" is on the extreme right.