Question

7. A hollow sphere has outer diameter 25m and inner diameter 24m. Find the
total surface area​

Answer 1

Step-by-step explanation:

ANSWER

Internal diameter of spherical vessel =24 cm

External diameter of hemispherical vessel =25 cm

Internal radius =r=12 cm and External radius =R=12.5 cm

Total surface area to be painted

= External curved surface + Internal curved surface + Area of ring

=2πR

2

+2πr

2

+π(R

2

−r

2

)

=π(2R

2

+2r

2

+R

2

−r

2

)

=π(3R

2

+r

2

)

=

7

22

(3×12.5

2

+12

2

)

=

7

22

(468.75+144)

=

7

22

×612.75

=1925.78sq.cm

Rate of painting =5paise per sq.cm

Thus, cost of painting=Area×Rate=

100

1925.78×5

=Rs.96.29

Answer 2

Answer:

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