A spherical ball of lead, 3 cm in diameter, is melted and recast into three spherical balls. The diameters of two of these balls are \(\frac{3}{2}\) cm and 2 cm, respectively. Find the diameter of the third ball.  

This question was previously asked in
SSC CGL 2023 Tier-I Official Paper (Held On: 17 Jul 2023 Shift 4)
View all SSC CGL Papers >
  1. 2.1 cm
  2. 3.3 cm
  3. 3 cm
  4. 2.5 cm

Answer (Detailed Solution Below)

Option 4 : 2.5 cm
ssc-cgl-offline-mock
Free
SSC CGL Tier 1 2025 Full Test - 01
3.8 Lakh Users
100 Questions 200 Marks 60 Mins

Detailed Solution

Download Solution PDF

Given:

Diameter of spherical ball (D)= 3 cm

Diameter of 1st small ball (D1)= 1.5 cm

Diameter of 2nd small ball (D2)= 2 cm

Concept used:

Total volume of small spherical balls = Volume of large spherical balls

Formula used:

Volume of spherical ball = (4/3) × π × R3

Calculation:

Let, the diameter of 3rd small spherical ball = D3

Volume of (1st small spherical ball + 2nd spherical ball + 3rd spherical ball) = volume of large spherical ball

⇒ 4/3 π × (D1/2)3 +  4/3 π × (D2/2)3 + 4/3 π × (D3/2)3 = 4/3 π (D/2)3

⇒ 4/3 π × [(1.5/2)3 + (2/2)3 + (D3/2)3 ]= 4/3 π (3/2)3

⇒ [(3.375/8) + 1 + (D3/2)3 ] = 3.375

⇒ (D3/2)3 = 2.375 - (3.375/8)

⇒ (D3/2)3 = (19 - 3.375)/8

⇒ D3 = 3√15.625 = 2.5

∴ The correct answer is 2.5.

Latest SSC CGL Updates

Last updated on Jul 22, 2025

-> The IB Security Assistant Executive Notification 2025 has been released on 22nd July 2025 on the official website.

-> The SSC CGL Notification 2025 has been announced for 14,582 vacancies of various Group B and C posts across central government departments.

-> The SSC CGL Tier 1 exam is scheduled to take place from 13th to 30th August 2025 in multiple shifts.

-> In the SSC CGL 2025 Notification, vacancies for two new posts, namely, "Section Head" and "Office Superintendent" have been announced.

-> Candidates can refer to the CGL Syllabus for a better understanding of the exam structure and pattern.

-> The CGL Eligibility is a bachelor’s degree in any discipline, with the age limit varying from post to post. 

-> The SSC CGL Salary structure varies by post, with entry-level posts starting at Pay Level-4 (Rs. 25,500 to 81,100/-) and going up to Pay Level-7 (Rs. 44,900 to 1,42,400/-).

-> Attempt SSC CGL Free English Mock Test and SSC CGL Current Affairs Mock Test.

More Mensuration Questions

Get Free Access Now
Hot Links: teen patti master gold apk teen patti master gold teen patti master 51 bonus teen patti app teen patti master apk