Question

(27) The diameter of a sphere is decreased by 25 %. By
what percent does its curved surface area decrease ?
​

Answer 1

$\huge{\overline{\underline{\bf{ANSWER}}}}$

GIVEN,

radii is decreased by 25%

TO FIND,

%Of csa decreased

SOLUTION,

let the initial radii be x

CSA = 4π$\{x}^2$______(1)

when radii decreased by 25%

x-25%of x

x-$\25/100$

x-$\25/100$

$\div{3x/4}$

CSA when 25 % of radii is decreased=

CSA = 4π$\div{3x/4}^2$

CSA=4π$\div{9x^2/16}$_____(2)

from (1) and (2)

CSA decreased =

$\div{4π\div{9x^2/16}/{4πx^2}$×100

56.25%

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