Question

The difference between outside and inside surfaces of a cylindrical metallic pipe 14cm long is 44 cm2. If the pipe is made of 88 cm3 of metal, find the outer and inner radii of the pipe​

Answer 1

Answer:

Outer radius = 5/2 cm

Inner radius = 2 cm

Answer 2

Answer: External radius=5/4

Internal radius=11cm

Step-by-step explanation:

Let, R be the external radius and r be the inner radius of the metallic pipe. h=14cm

Outer surface area−inner surface area=44cm^2

Therefore,2πRh−2πrh=44cm^2

R−r= $\frac{44}{2*\frac{22}{7} *14} =\frac{44*7}{2*22*14}$

=R-R = 1/2

The volume of metal used =88cm^3

∴ External volume − internal volume =88cm^3

Therefore,πR^2h−πr^2h=88cm^3

∴πh(R^2−r^2)=88cm^3

$\frac{22}{7} *14(R+r)(R-r)=88cm^3$

22*2(R+r)1/2=88cm^3

Therefore, R+r=88/22=4

R+r=4

R-r=1/2

2R=5/2

R=5/4cm

External radius=5/4

R+r=5/4

5/4+r=4

5+r=16

r=16-5

r=11

Internal radius=11cm