Answer:
44 1/3 cm
Step-by-step explanation:
The cube has an edge length of ∛0.027 m = 0.3 m, so a center of mass (CoM) 15 cm above the floor.
The sphere's center of mass is 40 cm above the top of the cube, so is 70 cm above the floor. The weighted average of the CoM locations is ...
((15 cm)(0.700 kg) +(70 cm)(0.800 kg))/(0.700 kg +0.800 kg)
= (10.5 kg·cm +56 kg·cm)/(1.500 kg) = 44.333... cm
The center of mass of the two-object system is 44 1/3 cm above the floor.