To determine the velocity of 2 g marble after the collision, we use the equation for conservation of momentum.
Momentum before the collision= Momentum after the collision.
.
Here,
is the mass of larger marble,
is the mass of smaller marble,
is the velocity of the larger marble and
is the velocity of smaller marble before collision and
is the velocity of the larger marble and
is the velocity of smaller marble after collision.
Given,
,
,
,
,
and
.
Substituting these values in above equation,

Thus, the velocity of 2 g marble after the collision is
