The task is to generate the correct answer for a given math problem.

[EX Q]: Problem: a , b and c , each working alone can complete a job in 6 , 8 and 12 days respectively . if all three of them work together to complete a job and earn $ 1170 , what will be b ' s share of the earnings ?
[EX A]: $ 390

[EX Q]: Problem: a worker is paid a regular rate of rs . 30 for completing a survey . the worker completes 100 surveys per week . for any survey involving the use of her cellphone , she is paid at a rate of that is 20 % higher than her regular rate . if she completed 50 surveys involving the use of her cellphone , how much did she get that week ?
[EX A]: 330

[EX Q]: Problem: a cylindrical bucket of height 36 cm and radius 21 cm is filled with sand . the bucket is emptied on the ground and a conical heap of sand is formed , the height of the heap being 12 cm . the radius of the heap at the base is :
[EX A]:
63 cm', 'b ) 53 cm', 'c ) 56 cm', 'd ) 66 cm', 'e ) none of these'