Question
Download Solution PDFA boat can go 3 km upstream and 5 km downstream in 55 minutes. It can also go 4 km upstream and 9 km downstream in 1 hour 25 minutes. In how much time (in hours) will it go 43.2 km downstream?
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFLet the speed of boat and current be x km/hr and y km/hr respectively.
Downstream speed = (x + y) km/hr
Upstream speed = (x – y) km/hr
According to the question
3/(x – y) + 5/(x + y) = 55/60 = 11/12
4/(x – y) + 9/(x + y) = 1 + 25/60 = 17/12
Let 1/(x + y) = a and 1/(x – y) = b
3b + 5a = 11/12 ...1)
4b + 9a = 17/12 ...2)
Multiply by 4 in equation (1) and multiply by 3 in equation (2)
12b + 20a = 11/3 ...3)
12b + 27a = 17/4 ...4)
Subtract equation (3) from equation (4)
7a = 17/4 – 11/3
⇒ 7a = 7/12
⇒ a = 1/12
Since, 1/(x + y) = a
⇒ x + y = 1/a = 1/(1/12)
⇒ x + y = 12 km/hr
Speed of downstream = 12 km/hr
∴ Time taken to cover 43.2 km distance in downstream = 43.2/12 = 3.6 hrLast updated on Jul 17, 2025
-> This year, the Staff Selection Commission (SSC) has announced approximately 14,582 vacancies for various Group B and C posts across government departments.
-> The SSC CGL Tier 1 exam is scheduled to take place from 13th to 30th August 2025.
-> UGC NET Result Date 2025 Out at ugcnet.nta.ac.in.
-> Aspirants should visit ssc.gov.in 2025 regularly for updates and ensure timely submission of the CGL exam form.
-> 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.
-> Candidates selected through the SSC CGL exam will receive an attractive salary. Learn more about the SSC CGL Salary Structure.
-> Attempt SSC CGL Free English Mock Test and SSC CGL Current Affairs Mock Test.
-> The Bihar Sakshamta Pariksha Admit Card 2025 for 3rd phase is out on its official website.