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	Choose the correct choice from the following answers
A) 3.496 kg	B) 3.696 kg	C) 3.690 kg	D) 9.696 kg	E) 3.296 kg

Rationale: 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
Answer: B