Advertisements
Advertisements
प्रश्न
A wooden bookshelf has external dimensions as follows: Height = 110 cm, Depth = 25 cm, Breadth = 85 cm in following figure. The thickness of the plank is 5 cm everywhere. The external faces are to be polished and the inner faces are to be painted. If the rate of polishing is 20 paise per cm2 and the rate of painting is 10 paise per cm2. Find the total expenses required for polishing and painting the surface of the bookshelf.
Advertisements
उत्तर
External length of book shelf = 85cm = l
Breadth= 25cm
Height = 110cm.
External surface area of shelf while leaving front face of shelf
`=lh+2(lb+bh)`
`=[85xx110+21(85xx25+25xx110)]"cm"^2`
`= 19100"cm"^2`
Area of front face = `(85xx110-75xx100+2(75xx5))"cm"^2`
`=1850+ 750"cm"^2`
`=2600"cm"^2`
Area to be polished = `19100+2600"cm"^2`
`=21700"cm"^2`
Cost of polishing `1"cm"^2`"area" = "Rs". 0.20
Cost of polishing `21700"cm"^2 `are `= "Rs".[21700xx0.20]`
`= "Rs". 4340`
Now, length (l), breath (b), height (h) of each row of book shelf is 75cm, 20cm and 30cm
`((110-20)/3)` respectively.
Area to be painted in row `= 2(l+h)b+lh`
`=[2(75+30)xx20+75xx30]"cm"^2`
`=(4200+2250)"cm"^2`
`=6450"cm"^2`
Area to be painted in 3 rows `=(3xx6450)"cm"^2`
`=19350"cm"^2`
`"Cost of painting" 1"cm"^2 area = Rs. 0.10`
`"Cost of painting 19350 area" = Rs.(19350 xx 0 .10) - "Rs".1935`
Total expense required for polishing and painting the surface of the bookshelf
= Rs.(4340 +1935) = Rs. 6275.
APPEARS IN
संबंधित प्रश्न
The length, breadth and height of a room are 5 m, 4 m and 3 m respectively. Find the cost of white washing the walls of the room and the ceiling at the rate of Rs 7.50 per m2.
Mary wants to decorate her Christmas tree. She wants to place the tree on a wooden block
covered with coloured paper with picture of Santa Claus on it. She must know the exact
quantity of paper to buy for this purpose. If the box has length, breadth and height as 80
cm, 40 cm and 20 cm respectively. How many square sheets of paper of side 40 cm would
she require?
The length and breadth of a hall are in the ratio 4: 3 and its height is 5.5 metres. The cost of decorating its walls (including doors and windows) at Rs. 6.60 per square metre is Rs. 5082. Find the length and breadth of the room.
How many bricks each of size 25 cm × 10 cm × 8 cm will be required to build a wall 5 m long, 3 m high and 16 cm thick, assuming that the volume of sand and cement used in the construction is negligible?
An 8 m long cuboidal beam of wood when sliced produces four thousand 1 cm cubes and there is no wastage of wood in this process. If one edge of the beam is 0.5 m, find the third edge.
Find the surface area of a cuboid whose length = 6 dm, breadth = 8 dm, height = 10 dm.
A tank open at the top is made of iron sheet 4 m wide. If the dimensions of the tank are 12 m × 8 m × 6 m, find the cost of iron sheet at Rs 17.50 per metre.
Three cubes of each side 4 cm are joined end to end. Find the surface area of the resulting cuboid.
If each edge of a cube, of volume V, is doubled, then the volume of the new cube is
The number of cubes of side 3 cm that can be cut from a cuboid of dimensions 10 cm × 9 cm × 6 cm, is ______.
