Consider 4 (dimensionless) flies, 2 males and 2 females. They are situated at the four corners of a square of side 10 meters, the two males at diagonally opposite ends. At any time, each fly tries to reach the male-female fly in front of her-him using the shortest possible route. Since the flies are flying towards another, they will meet each other at a certain time at the center of the square. What is the length of the path that each has traveled at the moment they reach each other?

a) 12.5 mts
b) 10 mts
c) 7.5 mts
d) 5 mts
e) None of these

Consider 4 (dimensionless) flies, 2 males and 2 females. They are situated at the four corners of a square of side 10 meters, the two males at diagonally opposite ends. At any time, each fly tries to reach the male-female fly in front of her-him using the shortest possible route. Since the flies are flying towards another, they will meet each other at a certain time at the center of the square. What is the length of the path that each has traveled at the moment they reach each other?

a) 12.5 mts
b) 10 mts
c) 7.5 mts
d) 5 mts
e) None of these

The question seems a bit odd, really...

but i am wrong or isn't the distance 1/2 of the diagonal, i.e. 1/2 of the hypethenuse of the triangle with sides 10:10:10*root of 2, i.e, 5*root of 2?

What is the length of the path that each has traveled at the moment they reach each other?

As the question is worded, it doesn't make any sense; we need to know the direction in which the flies are facing to know which fly is "in front of her-him". If the flies on the leftmost corners are facing each other, for example, they will fly directly towards each other and will never reach the center. If the flies all begin by facing towards the center of the square, the setup doesn't make sense. I'm sure the intention is that each fly is facing in a different direction (one north, one east, one south and one west), though you then get a problem far out of the scope of the GMAT.