CLEAR
Toprankers-Info

+91 7676564400

Mobile App

Get it on Google Play
Discussions
Tags:

Articles

Discussions
Submit Discussion
NILOFAR I

· started a discussion

· 1 Months ago

doubt (Question: 338593.0 )

can u explain the trick once again clearly

Question:
Train A travelling at 63 kmph takes 27 sec to cross Train B when travelling in opposite direction whereas it takes 162 seconds to overtake it when travelling in the same direction. If the length of train B is 500 meters, find the length of Train A.
Options:
A) 100 m
B) 810 m
C) 500 m
D) 310 m
E) None of these
Solution:

Let the length of Train A be k meters 

Let speed of Train B be y kmph


Case 1 : 

Relative speed of 2 trains = 63 + y 

Time taken to cross = 27 sec or 27/3600 hrs

Relative distance between 2 trains = (k + 0.5) km

Therefore, k + 0.5 = (63 + y) \(\cfrac{27}{3600}\) ----- (1)


Case 2 : 

Relative speed of 2 trains = 63 – y 

Time taken to overtake = 162 sec or 162/3600 hrs

Relative distance between 2 trains = k + 0.5

Therefore, k + 0.5 = (63 – y) \(\cfrac{162}{3600}\)  --- (2)


From (1) and (2), solve for y.

(63 + y) 27 = (63 – y) 162 

27y + 162 y = (63 x 162) – (63 x 27) 

189y = 63 x 135 or y = 45 kmph


Substitute in (2) to get k.

k + 0.5 = (63 – 45) \(\cfrac{162}{3600}\) 

k = 310m

-logo
We at aim to provide most comprehensive content & test for practice which is carefully divided into various chapters and topics to help you focus on your weak areas.Our Practice mock test gives you unmatched analytics to help you realize your strong areas,time management and improvement areas.Our Short & Crisp notes on each topic will help you to quickly revise the topic along with the tips & tricks of the exams.
More About
-Info
-Info

Mobile App

Get it on Google Play
About Us Campus Ambassador Careers Contact Us Refund Policy

All Rights Reserved Top Rankers

User Policy
Disclaimer
Terms & Conditions