Question

A metal pipe is 7m long the cross section has inner diameter 2m and outer diameter 2.2m. find the cost of painting the pipe from both sides at the rate of 10persqm

Answer 1

L=7

D=2.2 so Radius =d/2

R=1.1

area of curved surface =2×22/7×rh

2×22/7×1.1×7

=2×22×1.1=48.4sqm it is outer surface of area of pipe

now we inner surface area

L=7

D=2 so radius =1

find the area

2×22/7×1×7

2×22=44sqm it is inner part of area of pipe

add total area

44+48.4=92.4sqm

the rate of panting is RS 10/sqm

92.4×10

RS=924

Answer 2

Length=7m

Diameter=2.2m

Radius=d/2

Radius= 2.2/2= 1.1

Radius=1.1

Area of curved surface =2×22/7xrh

2×22/7×1.1×7

=2×22×1.1=48.4m² it is outer surface of area of pipe

Now we inner surface area

Length=7

Diameter=2

Radius =1

find the area

2x22/7x1x7

2×22=44m² it is inner part of area of pipe

add total area

44+48.4-92.4m²

the rate of panting is RS 10 m²

92.4×10

RS=924