We assume that the prism being referred in this item may be any prism. For our case, we take both prisms to be rectangular prism so that the volume is equal to, V = L x W x H The dimensions of the prisms, (1) 10 cm x 10 cm x 24 cm (2) 5 cm x 20 cm x 24 cm
The circumference is the diameter multiplied by pi, and the radius is half of the diameter. If we divide 241.37 by pi we get a diameter of 77, and half of that is the radius, which is 38.5.
The answer would be 45 weeks, since you do 530-80 since that is the part the parents will foot, which will be 450 left. Then you do that divided by 10 since you plan to save 10 dollars a week and therefore are left with 45 weeks.