Task: Question Answering
Input (English): Problem: the weight of a hollow sphere is directly dependent on its surface area . the surface area of a sphere is 4 π · 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 ? 
Options: a ) 16 , b ) r = 32 , c ) r = 64 , d ) 128 , e ) 512
Output (English): b