If Ishwar covers 721 km in a boat in 42 hours against the stream and he takes 15 hours with the stream, then find the speed of the stream.

This question was previously asked in
RRB NTPC Graduate Level CBT-I Official Paper (Held On: 05 Jun, 2025 Shift 1)
View all RRB NTPC Papers >
  1. 15.45 km/hr
  2.  7.38 km/hr
  3.  22.48 km/hr
  4. 19.25 km/hr

Answer (Detailed Solution Below)

Option 1 : 15.45 km/hr
Free
RRB NTPC Graduate Level Full Test - 01
2.4 Lakh Users
100 Questions 100 Marks 90 Mins

Detailed Solution

Download Solution PDF

Given:

Distance against stream = 721 km

Time against stream = 42 hours

Distance with stream = 721 km

Time with stream = 15 hours

Formula used:

Speed = Distance ÷ Time

Speed in still water = (Downstream speed + Upstream speed) ÷ 2

Speed of stream = (Downstream speed - Upstream speed) ÷ 2

Calculation:

Upstream speed = 721 ÷ 42 = 17.166 km/h

Downstream speed = 721 ÷ 15 = 48.066 km/h

⇒ Speed of stream = (48.066 - 17.166) ÷ 2

⇒ Speed of stream = 30.9 ÷ 2 = 15.45 km/h

∴ The correct answer is \(15.45\) km/h.

Latest RRB NTPC Updates

Last updated on Jul 17, 2025

-> RRB NTPC Under Graduate Exam Date 2025 has been released on the official website of the Railway Recruitment Board.

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

-> UGC NET Result 2025 out @ugcnet.nta.ac.in

-> HSSC CET Admit Card 2025 has been released @hssc.gov.in

-> 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

->Bihar Police Driver Vacancy 2025 has been released @csbc.bihar.gov.in.

More Boat and River Questions

More Speed Time and Distance Questions

Get Free Access Now
Hot Links: teen patti live teen patti master download happy teen patti