Question

a rectangular board measure 21 m by 70 cm. circular plates are to be cut out from the board of Diameter 14 cm . how many plates can be cut and how much board will be left

Answer 1

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Answer 2

154 plates can be cut and 84 sq.cm. board will be left

Step-by-step explanation:

Length of rectangular board = 21 m = 2100 cm

Breadth of rectangular board = 70 cm

Area of board = $Length \times Breadth = 2100 \times 70 = 147000 cm^2$

Diameter of plate = 14 cm

Radius of plate =$\frac{14}{2} = 7 cm$

Area of plate =$\pi r^2 = \frac{22}{7} (7)^2 = 154 cm^2$

No. of circular plates can be cut =$\frac{147000}{154}=954.54 \sim 954$

Area of 954 plates = $154 \times 954 = 146916 cm^2$

Area of board left =$147000-146916= 84 cm^2$

Hence 154 plates can be cut and 84 sq.cm. board will be left

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