The weight of a hollow sphere is directly dependent on its surface area. The surface area of a sphere is 4π·R^2, where R is the radius of the sphere. If a hollow sphere of radius 0.15 cm made of a certain metal weighs 8 grams, a hollow sphere of radius 0.3 cm made of the same metal would weigh how many grams R?	Choose the correct answer:	A) 16	B) R=32	C) R=64	D) 128	E) 512
Weight directly proportional to 4 pi r^2   Now, 4pi is constant, so, weight is directly proportional to r^2.   When radius = 0.15, weight = 8, so (0.15) ^ 2 proportional to 8;   (0.15)^2 * 4 proportional to 8*4, solving further   (0.15)^2 * 2 ^2 = (0.15*2)^2 = 0.3 ^ 2; so answer = 32 (R=32)
<result>B</result>
The weight of a hollow sphere is directly dependent on its surface area. The surface area of a sphere is 4π·R^2, where R is the radius of the sphere. If a hollow sphere of radius 0.15 cm made of a certain metal weighs 8 grams, a hollow sphere of radius 0.3 cm made of the same metal would weigh how many grams R?