Question

a man Singh has 12 cylindrical pillar each having radius 50 cm and height 3.5 cm find the cost to paint the curved surface area of the pillars @ rupees 20 per metre square

Answer 1

Hi there !
Here's your answer

Given,
Radius of each pillar =50 cm = 0.5 m
Height = 3.5cm = 0.035m

Curved surface area of each pillar
= 2πrh
= 2 × 22/7 × 0.035 × 0.5 m
= 0.11m²

Curved surface area of 12 pillars = 0.11m² × 12

= 1.32 m²

Cost per m² = Rs 20
Cost for 1.32 m² = 1.32 × Rs 20

= Rs26.4

Thus,
the cost is Rs 26.4

Answer 2

aloha user!!
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thanks for asking this question.
here is the answer:

okay so there are 12 cylindrical pillars and each is having the radius 50cm and height 3.5 cm. we have got to find the cost of painting the curved surface area.

well, for this we are going to use the formula of curved surface area of cylinder
which is 2πrh.

the curved surface area of one of the cylindrical pillar would be
=> 2 × 22/7 × 50 × 3.5
=> 1100 cm²

now, for 12 of them:

=> 1100 cm² × 12 = 13200 cm²

the cost is given rupees 20 per m²

our answer is in cm² so we have got to convert it to meter. 

13200/ 10000 = 1.32 m²
perfect, now last step is to multiply it by 20 and we will get => rupees 26.40
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hope it helps :^)