Question

The length, breadth and height of a room are 5cm,4cm,3cm respectively. Find the cost of white washing the inner of the room and ceiling at the rate of ₹50 per square metre

Answer 1

Answer:

If  the length, breadth and height of a room are 5cm,4cm,3cm respectively.  

then the cost of whitewashing the inner of the room and ceiling at the rate of ₹50 per square metre is ₹3700.

Step-by-step explanation:

Area to be white washed does not include the floor.

Therefore area to be white washed = Area of four walls + area of the ceiling

$=2(l+b)\times h + l\times b\\=[2(5+4)\times 3 + 5\times4] m\\=2 \times9 \times3 + 20\\= 18 \times 3 + 20\\=54+20 sq m \\=74sq m$

Cost of white washing = ₹50 ×74= ₹3700

Answer 2

area of ceiling = L×B

4cm×3cm

12cm²

rate of washing ceiling =50×12= 600₹

area of opposite walls are equal

surface area of all walls = 2( L×H + B×H )

2(4cm×5cm+3cm×5cm)

2 (20cm²+15cm²)

2×35cm²

70cm²

rate of washing all walls= 70×50

3500₹

total cost for washing=3500+600

4100₹ans.