Answer:
2069 grams
Explanation:
Assume that the box itself is massless so the weight is only due to the spheres only. Calculate the volume of a solid sphere of radius 3 in:
Vout = (4/3)pi(3^3) = 36pi in^3
Now calculate the volume of a solid sphere of radius 2 in:
Vin = (4/3)pi(2^3) = (32/3)pi in^3
To calculate the volume of the hollow sphere, subtract Vin from Vout:
Vnet = Vout - Vin = (76/3)pi
Since the density of the plastic is 3.25 g/in^3, the mass of each hollow sphere is
m = (density) × Vnet = (3.25 g/in^3)×(76/3)pi
= 258.7 g
Since there are 8 spheres in a box, the total weight of the box is
M = 8m = 2069 grams