The difference between inside and outside surfaces of a cylindrical tube is 14 cm long is 88 sq.cm. If the volume of the tube is 176 cubic cm, Find the inner and outer radii of the tube.
Let, R be the outer radius
R be the inner radius
Here, h = 14 cm
2πRh - 2πrh = 88
⟹ 2πh(R – r) = 88
⟹ 2 * 22/7 * 14(R – r) = 88
⟹ (R – r) = 1cm .....1
Volume of tube $=\pi * R^{2} * h-\pi * r^{2} \star h$
$176=\pi h\left(R^{2}-r^{2}\right)$
$176=22 / 7^{*} 14\left(R^{2}-r^{2}\right)$
$\Rightarrow\left(R^{2}-r^{2}\right)=4$
⟹ (R + r)(R – r) = 4
Here, (R - r) = 1
⟹ (R + r) (1) = 4
⟹ (R + r) = 4 cm
⟹ R = 4 – r ....2
Here, R – r = 1
⟹ R = 1 + r
Substitute R value in eq 2
⟹ 1 + r = 4 – r
⟹ 2r = 3
⟹ r = 3/2
= 1.5 cm
Substitute ‘r’ value in eq 1
⟹ R – 1.5 = 1
⟹ R = 1 + 1.5
⟹ R = 2.5 cm
Hence, the value of inner radii is 1.5 cm and radius of outer radii is 2.5 cm