The length of a metallic pipe is 7.56 m. Its external and internal radii are 2.5 cm and 1.5 cm respectively. If 1 cm3 of the metal weight 7.5 g, then the weight of the pipe is: ( Take = 227 )

Answer: Option C

Solution

Answer: Option C

Solution:

V = π(R² - r²) × h
V = $$\frac{22}{7}$$ × 756(2.5² - 1.5²)
V = 22 × 108 × 4 × 1
V = 9484 cm³
The weight of the pipe
$$\begin{array}{rl}& =\frac{9484\times 7.5}{1000}\\ & =71.28\text{ kg}\end{array}$$