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 8g/ cm^3 , then the weight of the pipe is
Choose the correct choice from the following choices.
A) 4.996 kg B) 5.696 kg C) 3.796 kg D) 3.696 kg E) 3.996 kg
External radius = 4 cm,   Internal radius = 3 cm.   Volume of iron = [ 22/7 x (4 ^2 x 3 ^2) 21] cm^3 = 462 cm^3   Weight of iron = (462 x 8)gm = 3696 gm = 3.696 kg   ANSWER:3.696 kg
<result>D</result>
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 8g/ cm^3 , then the weight of the pipe is