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  1. If the radius of a circle be reduced by 50%. Its area is reduced by ?
    1. 31.5%
    2. 39.5%
    3. 34.5%
    4. 65.5%
Correct Option: C

Original area = π x (r/2)2 = πr2/4
Reduction in area = π r2 - 3π r2/4

∴ Reduction per cent = [ 3πr2/4 x 4/(πr2) x 100 ] %
= 75%


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