Question

A room is 8.5m long, 6.5m broad anf 3.4m high. It has 2 doors each measuring 1.5m by 1m and two windows each measuring 2m by 1m. Find the cost of painting its four walls at 160 rupees per metre

Answer 1

$\mathfrak{\purple {\huge{Hello\:Mate!!}}}$

$<b><u>Answer</u></b>$

$<b>The cost of painting the walls = ₹20,824</b>$

$<b><u>Step-by-step explanation</u></b>$

$<b>CSA of a cuboid = 2(LB+BH+HL)</b>$

CSA of the room = 2[(8.5m×6.5m) + (6.5m×3.4m) + (3.4m×8.5m)]

CSA of the room = $2[(55.25m^2) + (22.1m^2) + (28.9m^2)]$

CSA of the room = $2(106.25m^2)$

CSA of the room = $135.15m^2$

$<b><font color="pink">But there are two doors and two windows and we are not gonna to paint them. So, we have to subtract the area of doors and windows from theC.S.A of room.</font></b>$

$<b>The area of door = lb</b>$

Area of the door = 1.5m × 1m

Area of the door = $1.5m^2$

$<b>As there are two doors,</b>$

Then, the area of two doors = $1.5m^2 × 2$

The area of two doors = $3m^2$

$<b>The area of window = lb</b>$

The area of window = 2m × 1m

The area of window = $2m^2$

$<b>As there are two window,</b>$

Area of two windows = $2m^2 ×2$

Area of two windows = $4m^2$

$<b>The remaining area of the walls of the room will be,</b>$

CSA of the room - (area of doors + area of windows)

$135.15m^2 - (3m^2 + 2m^2)$

$135.15m^2 - (5m^2)$

$130.15m^2$

The cost of painting the walls = area × rate

The cost of painting the walls = $130.15m^2 × Rs. 160$

$<b>The cost of painting the walls = ₹20,824</b>$

Thanks...!

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