The speed of the smaller stone is given as two times the speed of the larger stone.
Let v be the initial velocity of the larger stone.
Then the initial velocity of the smaller stone is,
As the given kinematic equation is,
Where x is the distance travelled in the upward direction and g is the acceleration due to gravity.
For the smaller stone, the distance travelled is,
Thus, the distance travelled by the small stone in the upward direction is 4 times the distance travelled by the larger stone.