a hollow iron pipe is 21 cm long and its external diameter is 8 cm . if the thickness of the pipe is 1 cm and iron weighs , then the weight of the pipe is
explanation : external radius = 4 cm , internal radius = 3 cm . volume of iron = = weight of iron = ( 462 x 8 ) gm = 3696 gm = 3.696 kg answer : b ) 3.696 kg
divide(multiply(8, multiply(multiply(divide(add(21, const_1), add(const_4, const_3)), subtract(power(const_4, const_2), power(const_3, const_2))), 21)), const_1000)