Question

the diameter of sphere decrese by 25% by what percent does it curved surface area decrease​

Answer 1

Given diameter and also radius decreases by 25 %

Let initial CSA be S and final CSA be S'.

S is directly proportional to r²

S / S' = (100 / 75 )²

S / S' = 16 / 9

S' = 9S / 16

% Decrease

(S - S' / S) X 100

= [(S - 9S/16) / S ] X 100

= 7 X 100 / 16

= 43.75 % decrease