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    A cylindrical rod of radius 30 cm and length 40 cm is melted and made into spherical balls

    A cylindrical rod of radius 30 cm and length 40 cm is melted and made into spherical balls of radius 1 cm. The number of spherical balls is
    (a) 36000
    (b) 27000
    (c) 90000
    (d) 40000

    Asked by Anurag Mishra on 26th March 2016 in Maths.
    1 Answers
    Professor

    Answer: (b) 27000 

    Solution:-
    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.

    Answered by Anurag Mishra on 27th March 2016..