A black blackboard of side 5m50cm and4m40cm is to be painted find the cost at the rate of rupees 10 per square metre

1 thought on “A black blackboard of side 5m50cm and4m40cm is to be painted find the cost at the rate of rupees 10 per square metre”

1. Given :

   • Length of the blackboard = 5 m 50 cm
   • Breadth of the blackboard = 4 m 40 cm
   • Rate of painting the balckboard = Rs. 10

   To find :

   • Cost of painting the blackboard

   Concept :

   To find the cost of painting the balckboard :-

   • Find the area of the blackboard.
   • For that firstly we will convert the length and breadth of the blackboard from 5 m 50 cm and 4 m 40 cm into m.
   • To find the cost multiply the rate of painting by area of the blackboard

   → Formula to calculate area of rectangle :-

   [tex]\boxed{ \sf \pmb{Area \: of \: rectangle = l \times b}}[/tex]

   → Unit conversion :-

   • 1 cm = 0.01 m

   To convert the value from cm into m divide the value by 100.

   Solution :

   • Length = 5 m 50 cm

   → 50 cm = 50 ÷ 100 = 0.5 m

   → Length = 5 + 0.5 = 5.5 m

   • Length of the Blackboard = 5.5 m

   • Breadth = 4 m 40 cm

   → 40 cm = 40 ÷ 100 = 0.4 m

   → Breadth = 4 + 0.4 = 4.4 m

   • Breadth of the Blackboard = 4.4 m

   Area of the blackboard :-

   [tex] \\ \dashrightarrow \sf \quad Area \: of \: blackboard = l \times b[/tex]

   [tex] \\ \dashrightarrow \sf \quad Area = 5.5 \times 4.4[/tex]

   [tex] \\ \dashrightarrow \sf \quad Area = 24.2[/tex]

   • Area of blackboard = 24.2 m²

   Cost of painting the blackboard :-

   [tex] \\ \dashrightarrow \sf \quad Cost = Area_{(Blackboard)} \times Rate_{(Painting)}[/tex]

   [tex] \\ \dashrightarrow \sf \quad Cost = 24.2 \times 10[/tex]

   [tex] \\ \dashrightarrow \sf \quad Cost = 242[/tex]

   • Cost of painting the blackboard = Rs. 242

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   Know More :

   Some related formulae :-

   • Perimeter of reactangle = 2(l + b)
   • Diagonal of rectangle = √l² + √b²
   • Area of square = side × side
   • Perimeter of square = 4 × side
   • Diagonal of square = √2a
   • Total surface Area of cuboid = 2(lb + bh + hl)
   • Volume of cuboid = length × breadth × height
   • Perimeter of cuboid = 4 (length + breadth + height)
   • Total surface area of cube = 6 × side²
   • Volume of cube = side³
   • Perimeter of cube = 12 × side

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