Advertisements
Advertisements
Question
A classroom is 7 m long, 6 m broad and 3.5 m high. Doors and windows occupy an area of 17 m2. What is the cost of white-washing the walls at the rate of Rs 1.50 per m2.
Advertisements
Solution
\[\text { Length of the classroom = 7m } \]
\[\text { Breadth of the classroom = 6 }m\]
\[\text { Height of the classroom = 3 . 5 m }\]
\[\text { Total surface area of the classroom to be whitewashed = areas of the 4 walls }\]
\[ = 2 \times \text { (breadth } \times\text { height + length } \times \text { height })\]
\[ = 2 \times (6 \times 3 . 5 + 7 \times 3 . 5)\]
\[ = 2 \times (21 + 24 . 5)\]
\[ = 91 m^2 \]
\[\text { Also, the doors and windows occupy 17 } m^2 . \]
\[\text { So, the remaining area to be whitewashed }= 91 - 17 = 74 m^2 \]
\[\text { Given that the cost of whitewashing 1 } m^2\text { of wall = Rs }1 . 50\]
\[ \therefore \text { Total cost of whitewashing 74 } m^2 \text { of area } = 74 \times 1 . 50 = Rs 111\]
RELATED QUESTIONS
A cuboidal wooden block contains 36 cm3 wood. If it be 4 cm long and 3 cm wide, find its height.
Three cuboids of dimensions 5 cm × 6 cm × 7cm, 4cm × 7cm × 8 cm and 2 cm × 3 cm × 13 cm are melted and a cube is made. Find the side of cube.
Find the volume in cubic metre (cu. m) of the cuboid whose dimensions is length = 10 m, breadth = 25 dm, height = 50 cm.
The central hall of a school is 80 m long and 8 m high. It has 10 doors each of size 3 m × 1.5 m and 10 windows each of size 1.5 m × 1 m. If the cost of white-washing the walls of the hall at the rate of Rs 1.20 per m2 is Rs 2385.60, fidn the breadth of the hall.
The dimensions of a cinema hall are 100 m, 50 m and 18 m. How many persons can sit in the hall, if each person requires 150 m3 of air?
Three cubes of each side 4 cm are joined end to end. Find the surface area of the resulting cuboid.
Volume of a cuboid is 12 cm3. The volume (in cm3) of a cuboid whose sides are double of the above cuboid is
A tank 30 m long, 24 m wide, and 4.5 m deep is to be made. It is open from the top. Find the cost of iron-sheet required, at the rate of ₹ 65 per m2, to make the tank.
An open box of length 1.5 m, breadth 1 m, and height 1 m is to be made for use on a trolley for carrying garden waste. How much sheet metal will be required to make this box? The inside and outside surface of the box is to be painted with rust-proof paint. At a rate of 150 rupees per sqm, how much will it cost to paint the box?
Opposite faces of a cuboid are ______ in area.
