2. The length, breadth and height of a room are 5m, 4m and 3
respectively. Find the cost of white washing the walls of the room and
the ceiling at the rate of Rs. 7.50 per m
Answers
GIVEN :-
- Length (l) = 5m
- Breadth (b) = 4m
- Height (h) = 3m
- Cost of white washing is 7.5Rs/m².
TO FIND :-
- Cost of white washing the walls and ceiling.
TO KNOW :-
★ Lateral Surface Area of Cuboid = 2(lh+bh)
★ Area of base of Cuboid = lb
SOLUTION :-
We have to find the area of walls and the ceiling.
Area for white washing = L.S.A + base area
= 2(lh+bh) + lb
Putting values we get...
→ 2[ (5)(3) + (4)(3) ] + (5)(4)
→ 2[ 15 + 12 ] + 20
→ 2 [ 27 ] + 20
→ 54 + 20
→ 74m²
Hence , area of 74m² room is to be white washed at the rate of 7.5Rs/m².
_____________
We know ,
Cost of white washing is 7.5Rs per metre.
1m² → 7.5Rs
For 74m , Cost of white washing will be 7.5×74 Rs.
74m² → 7.5 × 74
ㅤㅤㅤ→ 555Rs
Hence , cost of white washing is 555Rs.
MORE TO KNOW :-
★ Area of cube = 6×edge²
★ Area of cylinder = 2πr(r+h)
★ Area of cone = πr(r+l)
★ Area of hemisphere = 3πr²
★ Area of sphere = 4πr²
Given :-
Length = 5m
Breadth = 4m
Height = 3m
To find :-
Cost of white washing of room and ceiling.
Using Formula :-
LSA of rectangle + Base Area
= 2h (l + b) + lb
Solution :-
Length = 5m
Breadth = 4m
Height = 3m
Area of white washing = 2h (l + b) + lb
= 2 × 3m (5m + 4m) + 5m × 4m
= 6m (9m) + 20m²
= 54m² + 20m²
= 74m²
Therefore,
Area of white washing = 74m².
Cost of white washing 1m² = Rs.7.50
Cost of white washing 74m² = 7.5 × 74 = 555
Therefore,
Cost of white washing = Rs.555