A cylindrical rod of radius 30 cm and length 40 cm is melted and made into spherical balls
Answer: (b) 27000
The radius of a cylindrical rod = 30 cm
And, height of the cylindrical rod = length of cylindrical rod = 40 cm
Then, the volume of the cylindrical rod = pai x (30)^2 x 40
= 36000 pai cm^2
The radius of spherical ball = 1 cm
Then, the volume of spherical ball = 4 pai x (1)^3/3
= 4 pai/3
So, the number of spherical balls = 36000 pai x 3/4 x pai
= 9000 x 3
= 27, 000
Then, the number of spherical balls is 27000.
Hence, the correct answer is option (b) 27000.