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The dimensions of a room are (9m × 8m × 6.5m). It has one door of dimensions (2m × 1.5m) and two windows, each of dimensions (1.5m × 1m). Find the cost of whitewashing the walls at ₹ 25 per square metre. |
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Answer» The dimensions of the room is Length = 9m Breadth = 8m Height = 6.5m We know that Area of four walls of the room = 2 (l + b) × h By substituting the values Area of the four walls of the room = 2 (9 + 8) × 6.5 On further calculation Area of the four walls of the room = 34 × 6.5 So we get Area of the four walls of the room = 221 m2 The dimensions of the door are Length = 2m Breadth = 1.5m We know that Area of one door = l × b By substituting the values Area of one door = 2 × 1.5 So we get Area of one door = 3m2 The dimensions of the window are Length = 1.5m Breadth = 1m We know that Area of two windows = 2 (l × b) By substituting the values Area of two windows = 2 (1.5 × 1) On further calculation Area of two windows = 2 × 1.5 = 3m2 So the area to be whitewashed = Area of four walls of the room – Area of one door – Area of two windows By substituting the values Area to be whitewashed = (221 – 3 – 3) So we get Area to be whitewashed = 215m2 It is given that the cost of whitewashing = ₹ 25 per square metre So the cost of whitewashing 215m2 = ₹ (25 × 215) Cost of whitewashing 215m2 = ₹ 5375 Therefore, the cost of whitewashing 215m2 is ₹ 5375. |
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