Latest TCS Aptitude Question SOLUTION: A fly is flying between two trains, each travelling towards each other on the same track at 60 km/h. The fly reaches one engine, reverses itself immediately, and flies back to the

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(#M40023817) TCS question Keep an EYE

A fly is flying between two trains, each travelling towards each other on the same track at 60 km/h. The fly reaches one engine, reverses itself immediately, and flies back to the other engine, repeating the process each time. The fly is flying at 90 km/h. If the fly flies 180 km before the trains meet, how far apart were the trains initially?

Asked In TCS Arpit Srivastava (10 years ago)

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roushan  (10 years ago)

Ans: 240km


let the reqiured distance be D.
relative speed of the trains = (60+60)
time taken by the two trains to meet = (total distance between them)/their relative speed =D/(60+60)...........(1)

speed of fly=90km/hr and distace travelled by it = 180.
so time for which it flies = 180/90= 2 ............(2)

from equation 1 & 2 we have...D/(60+60) = 2
=>D= 240

Is this solution Helpfull? Yes (35) | No (4)  

Karim Panjwani  (10 years ago)

its 240kms.

when fly flies first 90km, total distance traveled by both train is (60+60)=120km.
for next 90km by fly, trains again travel 120km, hence total distance between two trains initially is 120km + 120km = 240kms.

Is this solution Helpfull? Yes (7) | No (1)  

Shahroz Ahmed  (10 years ago)

240 kms as fly flies for 2hrs and relative speed is 120km/hr, so 120*2=240

Is this solution Helpfull? Yes (2) | No (1)  

Aman Kohli  (10 years ago)

time taken by the fly to cover 180km at speed 90km/h= D/T = 180/90 = 2hr
now as the train are travelling in opp direction so
relative speed = S1 + S2
= 60 + 60 = 120km/hr
Time = 2 hr ( equals the time taken by the fly cuz it will travel only till the
trains dun meet)

Distance = T * S
= 120 * 2
= 240km ANS.

Is this solution Helpfull? Yes (2) | No   

chirag jain  (10 years ago)

Relative speed of fly with any train= (90+60) = 150km/hr
Distance travelled= 180km
Time taken= 6/5hr..........eqtn 1

Now the relative speed of the trains are (60+60)= 120km/hr
So the distance will be= speed*time= 120*6/5= 144km..

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sayantan karmakar  (10 years ago)

what are the options

Is this solution Helpfull? Yes | No (1)  

Y.Prasanna Chandra Lekha  (10 years ago)

the fly took 2hrs to travel till they meet
hence the trains travelled for two hours with relative speed of 60+60=120kmph
distance they covered=initial distance=2*120=240km

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