Derek had a square box lid and 10 marbles. He placed all 10 marbles along the inside walls of the lid and had an equal number of marbles on each of the four sides. How many marbles were on each side?

Answer 1

OOO
O..O
OOO

OOOO
O.....O
O.....O
OOOO

I can't see how it is possible.

Answer 2

Put two in opposite corners, then two on each side. The corners ones touch two sides....resulting in three marbles on each side.