Question

The surface area of a solid sphere is increased
by 21% without changing its shape. Find the
thepercentage increase in its:
(i) radius
ii volume​

Answer 1

Previous surface area =x

then new surface are =1.21x

Now surface Area ∝(radius)

2

then

1.21x

x

=(

r

new

r

old

)

2

r

new

=1.1r

old

10% increase . in radius

Now volume ∝(radius)

3

then volume ∝(surfacearea)

3/2

V

new

v

old

=(

1.21x

x

)

3/2

V

new

=1.331V

old

33.1%increase in volume