The radius of the sphere initially was: (use π=22/7)

If the radius of a sphere is increased by 2 cm, then its surface area increases by 352 cm2. The radius of the sphere initially was: (use π=22/7)

  1. 3
  2. 4 cm
  3. 6 cm
  4. 5 cm
Anurag Mishra Professor Asked on 10th December 2015 in Maths.
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1 Answer(s)

Answer:  (3) 6 cm

Explanation:-
Let the radius of the sphere be R cm.

Formula-
The surface area of the sphere = 4 π R²

If the radius of the sphere increased by 2 cm, then its surface area increased by 352 cm².
Then,  4 π (R + 2)² – 4 π R² = 352
{(R + 2)² – R²} = 352 x 7/4 x 22
R² + 2² + 2 x 2 x R – R² = 28
4 + 4 R = 28
4 R = 28 – 4
4 R = 24
R = 24/4
R = 6 cm

Then, radius of the sphere is 6 cm.

Hence, correct answer is option (3) 6 cm.

Anurag Mishra Professor Answered on 10th December 2015.
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