Q3. A building has 14 cylindrical pillars, each of diameter 1m and height 4.5 m. The curved surface of all the pillars have to be painted leaving 15 cm from top and bottom. Find the cost of painting the pillars at the rate of Rs. 25 per m²
Answers
Answered by
6
The cost of painting is 4949.925 RS
Step-by-step explanation:
The radius of the pillars are 1/2 m
The height is 4.5 m
The number of pillars is 14
The CSA of one pillars =2πrh
2×22/7×1/2×45/10
99/7 m²
The CSA of all the pillars =14×99/7
=198m²
We will not paint the pillars 15 cm from the top and bottom
so the total are that will not be painted is =30 cm
30cm= 30/10⁴ =3/10³ m²
The are the should be painted is =198- 0.003 m²
=197.997 m²
The cost is = 25×197997/1000
= 4949.925 RS
The cost of painting is 4949.925 RS
Answered by
1
C.S.A. of cylindrical =2πrh
⇒ C.S.A. of are pillar =2×
7
22
×28×4=704cm
2
⇒ C.S.A. of 24 pillars =24×704=16896cm
2
=16896×10
−4
m
2
=1.69m
2
⇒ Total cost Rs. 8×1.69=Rs.13.52
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