📢 Too many exams? Don’t know which one suits you best? Book Your Free Expert 👉 call Now!

  • google app store apple app store
  • ✖

      Question

      A solid metallic sphere of radius 15 cm is melted and

      recast into spherical balls of radius 3 cm each. What is the ratio of the surface area of the original sphere and the sum of the surface areas of all the balls?
      A 1:5 Correct Answer Incorrect Answer
      B 5:27 Correct Answer Incorrect Answer
      C 1:10 Correct Answer Incorrect Answer
      D 3:40 Correct Answer Incorrect Answer

      Solution

      Let the number of the smaller sphere be 'x' Volume of the bigger sphere = x × (volume of the smaller sphere) (4/3)π 15^3 = x × (4/3)π 3^3 x = 125 So their are total 125 smaller spheres Now, The surface area of the larger sphere = 4π 15 ⇒ 900π Surface area of smaller sphere = 4π 3^2 ⇒ 36π Total surface area of 125 smaller spheres = 125 × 36π ⇒ 4500π Surface area of the bigger sphere : Surface area of all smaller spheres = 900π : 4500π ⇒ 1 : 5

      Practice Next
      ask-question