A plate of 5m x 2m size with uniform thickness, weighing 20 kg, is perforated with 1000 holes of 5cm x 2cm size. What is the weight of the plate (in kg) after perforation?
Given:
Original plate size = 5 m × 2 m = 10 m²
Weight before perforation = 20 kg
Each hole = 5 cm × 2 cm = 0.05 m × 0.02 m = 0.001 m²
Number of holes = 1000
Total area removed = 1000 × 0.001 m² = 1 m²
Concept Used:
Weight is proportional to area (since thickness is uniform).
Formula Used:
New weight = Original weight × (Remaining area / Original area)
Solution:
Remaining area = 10 m² – 1 m² = 9 m²
New weight = 20 × (9 / 10) = 18 kg
Correct Option: (D) 18kg
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