A few lead spheres of diameter 6 cm are dropped into a cylindrical beaker containing some water such that they are fully submerged. If the diameter of the beaker is 9 cm and the water level has risen by 32 cm, find the number of lead spheres dropped into the beaker.

This question was previously asked in
NTPC CBT-I (Held On: 4 Jan 2021 Shift 2)
View all RRB NTPC Papers >
  1. 14
  2. 18
  3. 15
  4. 16

Answer (Detailed Solution Below)

Option 2 : 18
Free
RRB NTPC CBT-I Official Paper (Held On: 4 Jan 2021 Shift 1)
100 Qs. 100 Marks 90 Mins

Detailed Solution

Download Solution PDF

Given:

The radius of the sphere is 3 cm

Radius & height of cylinder are 4.5 cm & 32cm

Formula used:

The volume of sphere = 4/3πr³

The volume of cylinder = πr²h

Calculations:

The volume of sphere inserted = volume of water risen

Radius of sphere = 6/2= 3 cm

Radius of cylinder = 9/2 = 4.5

So,

(4/3)π × (3)³ × Number of sphere =  π (4.5) × (4.5) × 32

⇒ Number of sphere = 18

∴ The correct choice is option 2.

Latest RRB NTPC Updates

Last updated on Jun 27, 2025

-> RRB NTPC Under Graduate Exam Date 2025 will be out soon on the official website of the Railway Recruitment Board. 

-> RRB NTPC Exam Analysis 2025 is LIVE now. All the candidates appearing for the RRB NTPC Exam 2025 can check the complete exam analysis to strategize their preparation accordingly. 

-> The RRB NTPC Admit Card will be released on its official website for RRB NTPC Under Graduate Exam 2025.

-> Candidates who will appear for the RRB NTPC Exam can check their RRB NTPC Time Table 2025 from here. 

-> The RRB NTPC 2025 Notification released for a total of 11558 vacancies. A total of 3445 Vacancies have been announced for Undergraduate posts like Commercial Cum Ticket Clerk, Accounts Clerk Cum Typist, Junior Clerk cum Typist & Trains Clerk.

-> A total of 8114 vacancies are announced for Graduate-level posts in the Non-Technical Popular Categories (NTPC) such as Junior Clerk cum Typist, Accounts Clerk cum Typist, Station Master, etc.

-> Prepare for the exam using RRB NTPC Previous Year Papers.

-> Get detailed subject-wise UGC NET Exam Analysis 2025 and UGC NET Question Paper 2025 for shift 1 (25 June) here

More Mensuration Questions

Hot Links: online teen patti real money teen patti master download teen patti master