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# Aptitude - Problems on Trains - Discussion

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"Example is better than precept."
- (Proverb)
5.

A train passes a station platform in 36 seconds and a man standing on the platform in 20 seconds. If the speed of the train is 54 km/hr, what is the length of the platform?

 [A]. 120 m [B]. 240 m [C]. 300 m [D]. None of these

Explanation:

 Speed = 54 x 5 m/sec = 15 m/sec. 18

Length of the train = (15 x 20)m = 300 m.

Let the length of the platform be x metres.

 Then, x + 300 = 15 36

x + 300 = 540

x = 240 m.

 Saikiran said: (Wed, Jun 9, 2010 01:31:26 PM) Length of the train = (15 x 20)m = 300 m. how u took (15*20).

 Sivramakrishna said: (Fri, Jun 11, 2010 02:22:10 AM) How you took (15*20)?

 Gokul said: (Sun, Jun 13, 2010 07:23:12 AM) Guys I got the answer its because. Distance=Time*Speed.

 Sahil said: (Sat, Jun 19, 2010 06:19:39 AM) Distance= speed*time 300=15*20 this is length of a train only and we have to find out length of a plateform so we add length of both train and plateform becoz in case of bridge or plateform we can add both the length. then x+300/36=15 =240m

 Sheik said: (Wed, Jun 23, 2010 02:43:52 AM) Me also have the same doubt. Sahil, Dis= s*t is okay. Why didn't we take 300=15*36. Please explain.

 Shiva said: (Sat, Jun 26, 2010 12:04:13 PM) How is that you have taken (15 x 20) m as train length?

 Rajiv said: (Thu, Jul 1, 2010 11:29:29 AM) Why we do (15*20) ?

 Siva Krishna said: (Mon, Jul 5, 2010 04:45:02 AM) I have also same doubt explain me

 Vetri said: (Sat, Jul 10, 2010 12:54:41 PM) Train passes 36 sec but man standing 20sec so (36-20=16) speed= 15m/sec length=16*15=240m

 Priya said: (Sun, Jul 11, 2010 03:23:46 PM) Yeah the answer must be C. 300m.

 Sara said: (Sat, Jul 17, 2010 12:42:21 AM) We can take 15x20 as the train length only if the man is standing at the beginning of the platform. Am I correct.

 Anj said: (Wed, Jul 21, 2010 06:47:29 AM) The answer is perfectly right and logical.

 Rahul said: (Wed, Jul 28, 2010 03:17:03 PM) Length of the train is always calculated considering the train passes through a REFERENCE POINT. Here platform cannot be a REFERENCE POINT as it has some length. Thus man is taken as REFERENCE POINT to calculate the length of the train. Here train takes 20 seconds to cross REFERENCE POINT (man). Thus the train speed is multiplied by 20 seconds (15*20) to calculate the length of the train.

 Amit Kr. Soni said: (Fri, Aug 6, 2010 02:23:36 PM) Finally I solve question in my own language. Time to cross the man = 20 sec Speed of train = 54 km/hr, = 54*5/18, 15 m/sec .......... (1) Now length of train = 20*15 (fm distns = spd * time) = 300 mtr Now let length (ditns) of pltfrm = x mtr. Totl lenth (distns) = 300 + x Spd = 15 m/sec ........from eqan(1) According to question, 300 + x/15 = 36, [b'coz trn complet d totl distns in 36 sec] So x = 540 - 300 = 240 Answer

 Frank said: (Mon, Aug 23, 2010 08:17:43 AM) Whenever u get two timings subtract the highest from the lowest. Eg: 36 - 20 = 16 16*15 (after converting it to m/sec) = 240.

 Nagashree said: (Tue, Aug 24, 2010 12:10:09 PM) Here man is standing in the platform, and we have to calculate the length of platform. Hence we hav to multiply by 20 & not by36. Man in platform is reference point to us.

 Remy said: (Sat, Sep 4, 2010 07:51:01 AM) How come (300+x) /15?its not said the man stands at the beginning of platform. If hes somwhere in the middle how come we add the length of the train 300 m ?

 Gaurang said: (Wed, Sep 15, 2010 02:03:57 PM) Amit thanks for answer correctly.

 Magesh said: (Tue, Sep 21, 2010 08:16:07 AM) Guys listen. Take a point as man standing on the platform. So the moving train pass the point at the time of 20 sec. So, Length of the train = (15 x 20)m = 300 m.

 Karthik said: (Sun, Sep 26, 2010 08:11:38 AM) Shortcut: Minus the both time of the train to cross the platform as well as man (reference point). T = 36 sec, t = 20 sec. T - t = 16 sec. With the normal formula Length = Speed * Time (i.e) 15 m/s * 16 sec = 240 metres.

 Shelly said: (Sat, Nov 20, 2010 03:12:10 AM) Thanks Rahul.

 Vivek said: (Sat, Nov 20, 2010 10:15:50 PM) speed:- 54*5/18= 15 m/sec length of the train:-15*20= 300 m.(distance= speed * time) length of the platform:-x Speed = Distance /Time 15=300+x/36 300+x=540 x=540-300 x=240

 Kranthi said: (Fri, Nov 26, 2010 06:46:36 AM) As they asked only platform length why isn't it 35X15=540... why should we substract...??

 Satheesh said: (Mon, Nov 29, 2010 04:18:18 AM) Hi Guys 1 Km=1000 Meters 1 hr=3600 seconds If the speed of the train is 54 km/hr 54*1000= 54000 54000/3600=15 A train passes a station platform in 36 seconds 15*36=540 a man standing on the platform in 20 seconds 15*20=300 540-300=240 Ans:240 Simple

 Divya said: (Sat, Dec 4, 2010 01:14:16 PM) I solved in dis manner 54*(5/18)=15 speed =15m/sec it crossed d platform within 36 secs for 20 sec=? 36-20=16 16*15=240m

 Arun said: (Tue, Dec 7, 2010 02:43:05 PM) @divya :yeah... Its good..

 Kanth said: (Sat, Dec 11, 2010 08:17:59 AM) If the time taken by train to cross the man is 20 sec then u people cal length of train as distance = speed * time = 15 m/s * 20 sec = 300m similarly it is also given that train crosses the platform in 30sec then why not the length of the train is distance = speed * time = 15 m/s * 36 sec since both man an platform are stationary not moving . and the train is crossing the platform and man in same direction explain me some one plz ..... i very poor in aptitude .. i cant understand the logic

 Harsh said: (Sat, Dec 11, 2010 11:34:44 AM) Difference in time=16 So , (16/60)*54000m/60min

 Yohitha said: (Fri, Dec 17, 2010 12:09:58 AM) @frank. Thats the brilliant answer dude.

 Deepan said: (Fri, Dec 17, 2010 01:20:15 AM) Hai friends why (x+300)/36 = 15 ?

 Thangapandiyan said: (Mon, Dec 27, 2010 02:36:59 AM) We have add platform lengthe(x) + tranin length(300) = total lenght (because the train enginee is pass the platform in 36 sec not tail of the train) Now we using m/s = speed formula to find unknown platform length

 T Navakrishna said: (Wed, Feb 2, 2011 09:07:13 AM) As man length is negligible than the train length so length of the train crossing the person is 15*20. So time taken by the train is 20 sec and time taken by the train to cross the platform is 36 sec don't get get confused here.

 Nasir Shaikh said: (Sun, Feb 27, 2011 12:32:14 AM) Consider man is standing at the start of Platform,it takes 20 secs to cross man, but length of platorm is more than man. Length of train = 15 * 20 = 300 m But at 15 m/s train will last tip will take 16 more secs to cross platform i.e length of platform is 16 * 15 = 240 m

 Ankit said: (Wed, Mar 2, 2011 08:57:26 AM) Length of man is negligible in comparison to the train, so if cal len = 20. Then len will calculate to the train's actual lenght.

 Chalam said: (Sun, Mar 6, 2011 12:45:58 PM) Hi 36*54*5/18=540-> which is nothing but the total length includes train and plat form.... and 20*54*5/18=300 -> which is lenth includes train and up to man ..... and taking difference 540-300=240

 Suganthan.M said: (Wed, Mar 9, 2011 07:29:00 AM) Hi Guys speed=15 m/s A train passes the platform in 36 secs 15*36=540 a man standing on the platform in 20 secs 15*20=300 540-300=240 Ans:240 Am I right

 Nick said: (Sun, Mar 13, 2011 12:40:52 PM) Can any one explain me, if suppose ```l-------------------m------------l A B C l--------20S--------l------16S---l l---------------36s--------------l``` Train is takin 20s to pass the man and then 16s to pass the remaining platfom so it comes to 36s and the speed for train is 15m/s according to this it shoulb be 15*36= 540m 300m the point man is standing on platform and 240m for the remaining platform Therefore 300m+240m=540m the total lenght of platform.

 Mansoorkhan said: (Tue, Mar 15, 2011 01:48:41 AM) Vetri great simple explanation keep it up thanks to all.

 Raul said: (Wed, Apr 13, 2011 03:01:10 AM) Its simple and great explanation

 Afroz Khan said: (Sat, Apr 23, 2011 06:01:45 PM) Hello everyone. Which is the right answer, I can understand the login given by you people, but the question raised by nick is absolutely correct. Can someone explain me in more detail so that I could clear my doubts.

 Jagadeesh said: (Wed, Apr 27, 2011 03:50:52 AM) Hey guys u can do like this u can take the diffeerence between times i.e 36-20=16 seconds u can change 54km/hr as meters 54*5/18=15 16*15=240meters

 Kirankumar said: (Fri, May 6, 2011 06:29:49 AM) Hi afkhan according to nick The train takes to cross it self 20 The remaining 16 for platform Refer point no 4 in formulae.

 Sid said: (Wed, May 25, 2011 12:33:12 PM) Satheesh your answer is simply super. Thank you.

 Sabarish said: (Fri, Jun 10, 2011 09:38:31 AM) @saikiran here speed of the train given as in km/hr . so first we convert it into m/sec [i.e 54km/hr*(5/18)=15m/sec]. 5/18 is used to convert train speed into m/sec. Then if you want length of the train means,you;ll use below formula: Length of the Train=Speed*time It is general formula in train based questions.. Have a nice day for you..

 Suresh said: (Tue, Jul 12, 2011 02:22:53 AM) Satheesh your answer is very easy and simple way of maintain the problem solution. Thank you.

 Sachin Kamble said: (Wed, Jul 20, 2011 12:45:00 AM) Train passes the plat form in 36 sec and man standing on platform i.e 20 sec so the time 16 sec by 36-20=16 then apply speed=distance/time we have speed 54km/hr that to be converted in to m/sec because we need length in meter. So 54*[5/18] = 15 m/sec. Then distance = 16*15 = 240.

 Vivek said: (Sat, Jul 30, 2011 07:24:52 AM) Why we have multiplied with 20 means ... we have to take any one of the reference point. 36sec is train PASSES a station platform so we cant take. but here we can take it because man STANDING on the platform in 20 seconds. STANDING POINT is take it as reference point for calculating lengh of train.

 Sanjay Punj said: (Tue, Aug 2, 2011 11:40:19 AM) Thanks sachin kamble.

 Tara said: (Wed, Aug 3, 2011 04:17:22 PM) The above answer can be solved by Jagadeesh & Verti given method, i thinkg its also rite.

 Manonmani said: (Mon, Aug 8, 2011 03:11:13 PM) I also having doubt. Why we took 20 sec (300=20*15). Instead of 30sec (450=30*15).

 Pawan said: (Thu, Aug 11, 2011 10:44:51 AM) It is longest but easy to undertand len = speed*time speed: 54*5/18=15 Now calculate the length of train, len=15*20 =300 now calculate the length of platform use same formula (x=platform length) 300+x=15*36 x=540-300 x=240

 Satheesh.M said: (Mon, Aug 15, 2011 04:29:16 PM) Speed as we calculated 15m/sec The difference from the ref pt (i.e.,man) to the train pass the platform is 16 So, 15*16=240m

 Nusrath Kamal said: (Sat, Oct 29, 2011 11:09:43 AM) Why you all are complicating this simple question, here how this work: Answer = Length of the Train - Length of the platform Length of the Train= Speed + Time (please refer the formula). : 54 * 5/18 = 15(speed of the train)X 20 Time = 300 Length of the Platmform= Speed + Time : 54 * 5/18 = 15 (Speed of the Train) X 36 Time = 540 So answer = 540 - 300 = 240 M

 Ashwini Shet said: (Tue, Nov 15, 2011 02:28:57 PM) Is it necessary to calculate the length of the train? We can do it directly as: distance = speed * time Let x be the length of the platform , which train crosses in 36s. x = 54 *5/18 *36 = 240m

 Aasif Javed said: (Mon, Nov 21, 2011 05:43:41 PM) @Ashwini is your calculation right? Please check it. x = 54*5/18*36 = 540m not 240m

 Dheeraj said: (Mon, Dec 5, 2011 11:05:05 AM) Can some tell me which formula we are applying for for x+300 -----=15 36 I understood that once we multiply 15 and 36 we will get 540...... But, why we are multiplying them......? Is it because of distance = speed * Time.....??? Explain me please???

 Baskar.R said: (Sat, Dec 17, 2011 10:49:51 PM) Speed = 54x5m/sec = 15 m/sec 15*36=540 man standing= 15*20=300 ans= platform length=540-200 ans= 240

 Rahul said: (Mon, Dec 19, 2011 10:55:52 AM) Please tell me the reason why we can not calculate lenght of train through 15*36=540 can we calculate lenght of train like this if nt thn tell me reason.

 Ranjitha said: (Tue, Dec 27, 2011 11:52:49 AM) Actually the answer can b 540. 15*36=540.

 Mohd Imran said: (Wed, Jan 4, 2012 01:02:27 PM) Hi friends, length of the platform = speed*time so,speed =54km\hr 1km=1000 1hr=60*60=3600secs so,km/hr=1000/3600=5/18 km/hr=0.2777 so,speed =54*0.277=15 and time=36-20=16. so length of the platform=speed*time=15*16 length of the speed =240m. so the answer is(b)

 Sujay Kumar Sardar said: (Sun, Jan 8, 2012 09:43:37 PM) @Ranjita No Ranjita. 540m is the total distance(length) covered by train i.e its own Length plus length of the platform= 540m Though we know length of the train i.e 300m Therefore length of the platform is (540m-300m)= 240m.

 Rajasekhar Sarvepalli said: (Tue, Feb 14, 2012 04:08:40 PM) Since the train is moving toward the man you can do 36-20 seconds = 16 seconds. Logically if u think whenever u stand on a platform and train is coming towards you the the speed of a man becomes lesser than the speed of a train. there for distance = speed x time = (54 x 1000 meters/ 3600 seconds).x 16 sec = 15 x 16 = 240 meters

 Shro said: (Wed, Feb 15, 2012 06:11:47 PM) @ Rahul Nicely explained ...thank you :)

 Abhishek said: (Fri, Feb 17, 2012 04:27:46 AM) But we don't know where man is standing on the platform. Do we ? And if we don't know that then how do we supposed to do 15x20= 300 ? Can anyone tell me that. ?

 Shro said: (Fri, Feb 17, 2012 01:55:19 PM) @Abhishek here we are supposed to find the length of the platform. once we find the speed of train that is 15msec. length or distance=speed * time so length of train = speed of train is 15m/s multiplied by the train taking time to cross the man's position in 20secs. so= 15 * 20 If u calculate in this way ,then as per the mathematics , u will come to know where the man is standing.... In such cases Solve as per the formulas. Hope u got it :)

 Shakya said: (Sun, Feb 19, 2012 11:00:51 PM) You can take this question as:- A train can pass a station platform in 36 seconds and it can pass a man standing somewhere not only on platform (this statement shows the point is stationary) in 20 seconds. If the speed of the train is 54 km/hr, what is the length of the platform? speed=15 m/s train length=15*20; train length + platform length= 15*36=540; platform length = 540 - train length; platform length = 240 m (answer)

 Veeresh said: (Tue, Mar 6, 2012 09:58:35 PM) xkmph means train goes x meters in 3.6 seconds. here 36-20secs required to travel for the train to pass platform. 3.6 sec---->54 meters 16 secs---->? 16/3.6x54=240 meters

 Sudhapriya said: (Thu, Mar 15, 2012 08:44:18 PM) Thank you vetri. I gained answer from you.

 Praveen Prabhakar said: (Tue, Apr 10, 2012 07:32:46 PM) Distance=speed*time Distance=(54*5/18)*(36-20)=240m

 Prakash Ranjan Naik said: (Thu, Apr 12, 2012 12:30:04 PM) Train speed=15m/s Time=20s If train pass man means,that is the tme of train That's why Length of train=15x20

 Ravinder Kumar said: (Mon, Apr 23, 2012 07:26:32 PM) The simple method is Train speed is 54km/h*5/18=15m/second Time taken between man standing on platform and station platform ( 36-20) = 16 sec. Distance= 15*16 = 240m

 Gopu said: (Wed, May 9, 2012 11:15:58 AM) Simple method;. Convert train speed into m/sec=54*5/18. =15m/s. Subtract train time which it had taken to cross a man from the time taken by train to cross the platform i.e, = (36-20). =16. Now apply formula of distance i.e. speed*time. =15*16. =240. ) ).

 Shiji said: (Thu, May 17, 2012 10:42:00 AM) Why don`t we take the length of the train=15*36.

 Surender Kashyap said: (Tue, May 22, 2012 05:05:29 PM) L/20 = (L+P)/36 = 54*5/18 using compenondo and dividendo means (L+P)-L/36-20 P/16 = 15 SO, P = 15*16 P = 240

 Priyanka said: (Sat, Jun 9, 2012 10:24:49 AM) Train passes in 36 secs, man standing in 20 secs. therefor, 36-20= 16 secs. now, speed = 54 km/hr. = {54 X 5/18} = 15 m/sec. here, length = speed X time = 15 X 16 = 240 m. ans

 Guru said: (Tue, Jul 24, 2012 02:06:21 PM) The time taken by train to cross platform is=36-20=16sec. Speed of train=54*(5/18)m/s. Distance(length)=speed*time. =54*(5/18)*16. =240m.

 Kabita said: (Tue, Jul 24, 2012 02:41:45 PM) Train passes in 36 secs, man standing in 20 secs. Therefor, 36-20= 16 secs. Now, speed = 54 km/hr. = {54 X 5/18} = 15 m/sec. Here, length = speed X time = 15 X 16 = 240 m. ans

 Mamtha said: (Sat, Aug 4, 2012 12:10:00 PM) The train pass the man 20sec, and the train pass a station 36sec. So,36-20=16sec Then we know that speed of the train of the train is 54km/hr. =15m/sec Therefore, 16*15=240m. Answer.

 Muthu said: (Thu, Aug 9, 2012 02:36:57 PM) Train crossing station platform in 36 sec with speed of 54km/hr. Question asked what is the length of platform? 54 x 1000 /3600 = 15m/sec train travel distance. So for 36 sec train is crossing the platform. Total length of the platform is 36 x 15 = 540mts. If question asked what is the length of train then we have to calculate 20 sec X 15 m /sec = 300 mts. If asked what is the balance length of platform from man standing place, then (36-20= 16) 16 x 15 =240mts. I hope my view is correct.

 M.Ramya Devi said: (Sat, Aug 11, 2012 08:29:41 PM) Speed of the train=54km/hr. Speed=54*5/18=15. Train passes a station platform:Length=speed*time. =15*36=540. Train passes the man standing on the platform:Length=speed*time. =15*20=300. Length of the platform=540-300=240m.

 Sangram said: (Tue, Aug 14, 2012 09:16:17 AM) In simple process, Bs-------------------m------------Be A--------20S---------B------16S---C l---------------36s---------------l If man was reference point then T.P=36-20=16s. We know length=speed*time. Then lenth of train=(54*5/18)*16=15m/s.*16s.=240m. Answer=240m.

 Shantanu said: (Mon, Aug 27, 2012 05:28:20 PM) Why x and 300m are added?

 Praveen R said: (Wed, Oct 31, 2012 12:06:05 PM) Time taken for reach the platform=36sec. Time taken for reach a man= 16sec. Speed (S) = (54*5) /18=15. Distance between=36-20=16. Then the distance=16*15. =240.

 Shoeb said: (Wed, Nov 21, 2012 10:51:51 PM) Distance=Time*Speed. * 54 x 5/18 = 15 * 15 x 20(given) = 300 * x+300/36=15 =240m OR * Distance = speed*time * Distance = (54*5/18)*(36-20) = 15*16 = 240 Speed , Time is given to us. We have to only apply the formula in proper way.

 Suresh said: (Tue, Dec 25, 2012 07:30:47 AM) First we are calculate the length of train compared with a man standing on the platform. = (15*20) m. =300m. Second we are calculate the length of train compared with they passes a station platform. = (15*36) m. =540m. We wanted to the length of platform X. So, the length of platform X and the length of train compared with a man standing on the platform equal to the length of the train compared with they passes a station platform. X+300m=540m. X= (540-300) m. =240m. We were got the length of platform 240m.

 Srikanth said: (Sat, Feb 16, 2013 08:35:17 PM) Speed=54*(5/18)=15m/s. Now time = 36-20=16. Now distance(i.e length)=speed*time =15*16 =240m/s.