The pillars on the veranda of a school are square prisms of base length 20 centimetres and height 2.25 metres. There are 60 such pillars. What is the total cost of painting them all, at 250 rupees per square metre?

Open in App

Solution

Each side of the base of the pillar, a = 20 cm = 0.2 m (1 m = 100 cm)

Height of the pillar, h = 2.25 m

Surface area of a square prism = 2a(a + 2h)

∴ Surface area of the pillar = 2 × 0.2 × (0.2 + 2 × 2.25) m²

= 0.4 × (0.2 + 4.5) m²

= 0.4 × 4.7 m²

= 1.88 m²

Surface area of 60 such pillars = 60 × 1.88 m² = 112.8 m²

Cost of painting per square metre of the pillar = Rs.250

∴ Cost of painting 112.8 m²area of the pillars = Rs.250 × 112.8 = Rs.28200

Suggest Corrections

Similar questions

There are two water tanks atop a building, each of height 2 metres. One is a rectangular prism of base lengths 8 metres and 2 metres and the other is a square prism of base length 4 metres. What is the volume of each? What is the cost of painting the outer surface of each tank, at 250 rupees per square metre? Which costs less?

In a building, there are $24$ cylindrical pillars. For each pillar, the radius is $28 m$ and the height is $4 m .$ Find the total cost of painting the curved surface area of the pillars at the rate of $R s . 8$ per metre square

Q. Find the cost of painting 15 cylindrical pillars of a building at Rs 2.50 per square metre if the diameter and height of each pillar are 48 cm and 7 metres respectively.

A toy in the shape of a square pyramid has base edge 16 centimetres and slant height 10 centimetres. 500 of these are to be painted and the cost is 80 rupees per square metre. What would be the total cost?

Q. A mansion has

12

right cylindrical pillars each having radius

50 c m

and height

3.5 m

. Find the cost to paint the lateral surface of the pillars at Rs.

20

per square metre.

Join BYJU'S Learning Program