Heya User,
Answer the Question :-
In a building there are 24 cylindrical pillars with each having a radius 28 cm and height 4 m. Find the cost of painting the curved surface area of all pillars at the rate of Rs. 8 per meter square.
Answers
Radius of cylinderical pillars
= r = 28cm =0.28m
height ,h=4m
curved surface area of a cylinder =2πrh
curved surface area of a pillar= 2×22\6×0.28×4=7.04metresq.
Curved surface area of 24 such pillars = 7.04×24=168.96metresq.
cost of cementing an area of 1metresq. =Rs8
so,cost of painting 1689.6metresq.=168.96×8=Rs1,351.68
There are 24 cylindrical pillars .
We will find the CSA of each pillar .
Then multiply by 24 .
Then we will multiply the result with the required rate of cost .
Find the curved surface area of each pillar
Curved surface area = perimeter of cross section × height .
⇒ Curved surface area = 2 π r h
Radius of each sphere = 28 cm .
⇒ r = 28 cm
⇒ r = 0.28 m
Height of each sphere = 4 m .
C.S.A = 2 π r h
⇒ 2 × 22/7 × ( 0.28 ) × 4
⇒ 44/7 × 4 × ( 0.28 )
⇒ 176/7 × (0.28)
⇒ 176/7 × 28/100
⇒ 176 × 4/100
⇒ 176/25
⇒ 7.04
⇒ 7.04 m²
Find the total C.S.A of all pillars
Total C.S.A = 7.04 × 24 m²
⇒ 168.96 m²
Total cost
1 m² has a costing worth Rs 8 .
∴ 168.96 will require :
Total cost = Rs 8 × 168.96
⇒ Rs 1351.68