Task: Question Answering
Input (English): Problem: 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 8 g / cm 3, then the weight of the pipe is :
Options: a. 3.6 kg, b. 3.696 kg, c. 36 kg, d. 36.9 kg, e. none
Output (English): b