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
There are two cuboidal boxes as shown in the adjoining figure. Which box requires the lesser amount of material to make?
 |
 |
| (a) | (b) |
Water is pouring into a cubiodal reservoir at the rate of 60 litres per minute. If the volume of the reservoir is 108 m3, find the number of hours it will take to fill the reservoir.
What will be the height of a cuboid of volume 168 m3, if the area of its base is 28 m2?
A closed iron tank 12 m long, 9 m wide and 4 m deep is to be made. Determine the cost of iron sheet used at the rate of Rs 5 per metre sheet, sheet being 2 m wide.
On a particular day, the rain fall recorded in a terrace 6 m long and 5 m broad is 15 cm. The quantity of water collected in the terrace is
If V is the volume of a cuboid of dimensions x, y, z and A is its surface area, then `A/V`
The length, breadth, and height of a cuboid are in the ratio 6: 5 : 3. If its total surface area is 504 cm2; find its dimensions. Also, find the volume of the cuboid.
Find the volume of a cuboid whose diagonal is `3sqrt(29)"cm"` when its length, breadth and height are in the ratio 2 : 3 : 4.
The total surface area of a cuboid with dimension 10 cm × 6 cm × 5 cm is
Opposite faces of a cuboid are ______ in area.
