Answer:
the highest point above the ground = 0.48 m
Explanation:
lets ignore air friction, spring details,
The rest mass hanges 0.42 m above the floor and you pull 0.06 m below the original position, this is done by putting energy into the stratched spring so that when released the mass will compress the spring and cover a distance 0.06 m above the rest height.
then the highest point the mass will attain is 0.42 m + 0.06 m = 0.48 m above the ground.