so obviously first of all find three sherical objects or balls of varioius sizes to make it easier get a large medium and small sized.
then on scratch paper sketch those objects (im assuming by the looks of it you would trace them if not just draw them then take measuring tape or a ruler across to measure said object) now you arent told what units to measure in but id assume to stick with one unit either inches or cm
mesure the length across which is the circumference
now you would just have to do your calculations by finding the radius and volume and surface area
remember volume is (*units) cubed and suface area is (*units) sqared
