Question

find the cost of painting 18 cylindrical pillars of building at rupee 3. 50 per square metre...,if the diameter and height of each pillar is 42cm and 6m respectively.
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Answer 1

Answer: ₹498.96

Step-by-step explanation:

Diameter (d) = 42cm

Radius (r) = 42/2 = 21 cm = 21/100

= 0.21 m

Height (h) = 6 m

Curved Surface Area of cylinder

= 2πrh = 2×22/7×0.21×6

= 7.92 m2

Area of 18 pillars = 18×7.92

=142.56 m2

Cost of painting = ₹3.50×142.56

=₹498.96

Answer 2

Given :

• Diameter of cylindrical pillar = 42 cm; height = 6 m
• Cost of painting per square meter = Rs. 3.50

To Find :

• Cost of painting 18 cylindrical pillars.

$\huge\underline\green{\tt Solution:}$

→ Radius of each pillar

$=\dfrac{Diameter}{2}$

$=\dfrac{42}{2}$

$= 21\:cm$

∵ 1 m = 100 cm,

= 0.21 m

→ Area of one pillar = 2πrh

So,

For 18 pillars = 18 × 2πrh

$= 18\times 2\times\dfrac{22}{7}\times 0.21\times 6$

$= 142.56\:m^2$

→ Cost of painting 18 pillars

= 3.50 × 142.56

= ₹ 498.96

Answer : The cost of painting 18 such cylindrical pillars is ₹ 498.96

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