Mensuration Practice Test 10

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Question : 8 of 40

Marks: +1, -0

If the diameter of a sphere is decreased by 25%, its curved surface area will be decreased by:

43.25%
43.50%
43.75%
44.25%

Solution:

Let the diameter of the sphere = x
Radius =

x/2

Surface area =

4πr^2

=

4π(x/2)^2

=

πx^2

New diameter =

{3x}/4

So, new surface area =

4π({3x}/8)^2

=

{9πx^2}/{16}

It is reduced by

7/{16}

Percentage =

7/{16} × 100

= 43.75 %

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