Question

A spherical metallic shell with 6 cm external radius weighs 6688 g. What is the thickness of the shell if the density of metal is 10.5 g per cm3?

(Take π = 22/7)

A 4 cm Correct Answer Incorrect Answer
B 2 (1/2 )cm Correct Answer Incorrect Answer
C 3 cm Correct Answer Incorrect Answer
D 2 cm Correct Answer Incorrect Answer

Solution

⇒ Volume = (6688/10.5) Now, ⇒ (6688/10.5) = (4/3) × (22/7) × (6 - r ) ⇒ (63 - r3) = (6688 × 3 × 7)/(22 × 4 × 10.5) ⇒ (63- r3) = 152 ⇒ 216 - r3= 152 ⇒ r3= 216 - 152 ⇒ r3= 64 ⇒ r = ∛64 ⇒ r = 4 Now, ⇒ Thickness = 6 - 4 = 2 cm ∴ Thickness of the shell 2 cm

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