Question

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Answer 1

$\textbf {Question}$:

A building has 8 right cylindrical pillars whose cross sectional diameter is 1 m and whose height is 4.2 m. Find the expenditure to paint these pillars at the rate of ₹ 24 per m².

$\textbf {Solution}$:

Surface Area of the pillars = 8 × 2πrh

$\implies \sf 8 \times 2 \times \frac{22}{7} \times \frac{1}{ l2} \times {4.2} \\ \\ \implies \sf 13.2 \times 8 = 105.6 \:m^{2}$

Thus, the surface area of the pillars altogether is 105.6 m².

Now, cost of painting the pillars = Surface Area of the pillars × ₹24

$\sf \: 105.6 \times 24 = 2534.4$

Thus, the cost of painting the pillars is ₹2534.4.

Answer 2

Question :

A building has 8 right cylindrical pillars whose cross sectional diameter is 1 m and whose height is 4.2 m. Find the expenditure to paint these pillars at the rate of ₹ 24 per m².

Answer :

Rs 2534.4

Step-by-step explanation:

Since the building has to be painted , we need to find the surface area of each pillar.

The formula for the surface area is given by :

2 π r h

It is given that h = 4.2 m

r = diameter / 2

= > r = 1 m / 2 = 0.5 m

There are 8 pillars .

Surface area = 8 × 2 π × 0.5 m × 4.2 m

= > 8 × 2 × 22/7 × 1/2 × 4.2 m²

= > 8 × 22/7 × 4.2 m²

= > 105.6 m²

Cost per 1 m² = Rs 24 .

So cost per 105.6 m² = Rs 24 × 105.6

                                   = Rs 2534.4

Hence the cost will be Rs 2534.4