Question

A solid sphere of diameter 17.5 cm is cut into two equal halves. What will be the increase (in cm2) in the total surface area?

A) 289 B) 361.5 C) 481.25 D) 962.5

Answer 1

Answer:

We know,

Diameter / 2 = Radius

=⟩ 175 / 10 * 2 = Radius

=⟩ 8.75 cm = Radius

Hence, T.S.A ( Total Surface Area ) -- of the hemisphere =⟩ 1/2 [ 4 * π * r^2 ]

[ Hemisphere is considered in this case, since it is mentioned that the solid sphere is being into two halves ]

=⟩ 1/2 [ 4 * 22/7 * (8.75)^2 ]

=⟩ 1/2 [ 4 * 22/7 * (76.56) ]

=⟩ 1/2 [ 4 * 22 * 11 ]

( Since, 76.56 gets rounded off to the next non-decimal digit which is 77. It then gets cancelled on division by 7 )

=⟩ 1/2 * [968]

=⟩ 484 cm^2

( Note : In case, if the decimal point value was considered the answer would have been 481.25 cm^2 i.e., option C )

Thanks...!!