44 Views

Question : If a train 130 m long takes $6 \frac{1}{2}$ seconds to cross a man who is walking at 12 km/hr in the same direction in which the train going, then the speed of the train (in km/hr) is:

Option 1: 84

Option 2: 64

Option 3: 48

Option 4: 74


Team Careers360 23rd Jan, 2024
Answer (1)
Team Careers360 25th Jan, 2024

Correct Answer: 84


Solution : Man's speed in m/s = $12\text{ km/hr} \times \frac{5}{18} = 12 \times \frac{5}{18}\ \mathrm{ m/s} = \frac{10}{3}\text{ m/s}$
We know that the train crosses a 130-meter-long man in $\frac{13}{2}$ seconds.
$\therefore$ Relative speed = $\frac{130\ \mathrm{m}}{\frac{13}{2}\mathrm{s}} = 20\text{ m/s}$
Relative speed = (Train's speed in m/s) – (Man's speed in m/s)
$⇒20=$ (Train's speed in m/s) $-\frac{10}{3}$
$\therefore$ Train's speed in m/s = $20\text{ m/s} + \frac{10}{3}\text{ m/s} = \frac{70}{3} \text{ m/s}$
Now, Train's speed in km/hr = $\frac{70}{3} \times \frac{18}{5} = 84\text{ km/hr}$
Hence, the correct answer is 84.

How to crack SSC CHSL

Candidates can download this e-book to give a boost to thier preparation.

Download Now

Know More About

Related Questions

TOEFL ® Registrations 2024
Apply
Accepted by more than 11,000 universities in over 150 countries worldwide
Manipal Online M.Com Admissions
Apply
Apply for Online M.Com from Manipal University
View All Application Forms

Download the Careers360 App on your Android phone

Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile

150M+ Students
30,000+ Colleges
500+ Exams
1500+ E-books