a wooden bookshelf has external dimensions as follows height=110cm depth=25cm breadth=85cm .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 cm square and the rate of painting is 10 paise per cm square then find the total expenses required for polishing and painting the surface of the bookshelf
Answers
Answer:
Step-by-step explanation:
A book shelf is not a closed cuboid.
It is open on both ends.
The inner dimension of the shelf is :
Height = 110 - 10 = 100 cm
Width = 25 - 10 = 15cm
Length = 85 - 10 = 75 cm
Outer area :
2 × 85 × 110 = 18700 cm sq
2 × 25 × 110 = 5500 cm sq
Total area = 18700 + 5500 = 24200 cm sq
Inner area :
2 × 100 × 15 = 3000 cm sq
2 × 100 × 75 = 15000 cm sq
15000 + 3000 = 18000 cm sq
Amount required for polishing = 20 × 24200 = 484000 paise.
Amount required for painting = 10 × 18000 = 180000
Total :
180000 + 484000 = 664000 paise.
Answer:
664000 paise
Step-by-step explanation:
The area of Outer Cuboid is:
2( l + b) × h = 2(25 + 85) × 110 = 24200 cm²
So, the cost of polish = 24200 × 20 = 484000 paise
The area of Inner Cuboid is:
2( l + b) × h = 2(15 + 75) × 100 = 18000 cm²
So, the cost of paint = 18000 × 10 = 180000 paise
Thus, Total expense = 180000 + 484000 = 664000 paise