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# Aptitude - Problems on Trains - Discussion

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"No one is as deaf as the man who will not listen."
- (Proverb)
1.

A train running at the speed of 60 km/hr crosses a pole in 9 seconds. What is the length of the train?

 [A]. 120 metres [B]. 180 metres [C]. 324 metres [D]. 150 metres

Explanation:

 Speed= 60 x 5 m/sec = 50 m/sec. 18 3

 Length of the train = (Speed x Time) = 50 x 9 m = 150 m. 3

 Sundar said: (Wed, Jul 28, 2010 07:51:07 AM) Why we are multiplying the 60 with 5/18? The answer is simple. We are converting the 'kilo-meters/hour' value into 'meters/second'. Let me explain about converting km/hr into m/s in detail. 1 km = 1000 meters. 1 hr = 3600 seconds. 1 km/hr = 1000/3600 m/s = 10/36 m/s = 5/18 m/s. Therefore 1 km/hr = 5/18 m/sec. Similarly 60 km/hr = 60 x 5/18 m/sec. You may ask me, why should I convert it from km/hr to m/sec? Because, the time taken by the train is given in terms of seconds (9 seconds) and the 4 options are in terms of metres. But the speed of the train is given in terms of km/hr. So we have to convert the values from km/hr to m/s in order to find the solution in terms of metres/seconds. Hope you understand better. Have a nice day guys!

 Karthick said: (Thu, Jul 29, 2010 05:17:32 PM) Nice explanation for beginners.

 Dhesappan said: (Mon, Sep 27, 2010 06:16:53 AM) Any one know the how many feet is one meter?

 Sundar said: (Mon, Sep 27, 2010 08:43:50 AM) Feet to Meter conversion: 1 feet = 0.3048 meter Meter to Feet conversion: 1 meter = 3.28083 feet

 Jain Thomas said: (Fri, Nov 12, 2010 07:33:40 AM) Hi Sundar, That was a damn good explanation

 Rita said: (Fri, Nov 12, 2010 08:54:06 AM) Very well explained Sundar. Thanks a lot for helping us with your valuable explanation

 Kalimuthu said: (Wed, Nov 24, 2010 01:09:09 AM) 1000m=1km so 60000m goes in 1hour. 1 hour=3600 sec so 60000/3600 =16.666 so train cross in 1 second is 16.666m...so 9 seconds 16.6666*9=150meter .

 B.V.S.Sharma said: (Sat, Dec 4, 2010 08:48:54 AM) 60*5/18*9=150 m...

 Parashuram said: (Fri, Dec 10, 2010 07:34:38 AM) How to calculate 16*5/18*9?

 V.Navin Kumar said: (Thu, Dec 16, 2010 09:17:23 AM) Nice to learn fast.

 Naveen said: (Thu, Dec 30, 2010 12:33:56 AM) @B.V.S.Sharma 60*(5/18)*9=150 m...

 Poonam said: (Sun, Jan 2, 2011 09:19:45 AM) No need of MBA & MCA coaching classes. Thank you.

 Pooja said: (Sun, Jan 2, 2011 09:22:20 AM) Hi.Thank you for guiding students for MCA & MBA...

 Sunny said: (Fri, Jan 7, 2011 12:43:53 AM) Great Job Sundar and Naveen.Thank You.

 Vishnu said: (Sat, Jan 15, 2011 10:53:29 AM) Do any one know the relationship betwen miles and kilometers?

 Sudhakar said: (Tue, Jan 18, 2011 03:20:28 AM) It's useful to science students,and every student know the how to change the units. so thankyou very much sir.

 Sudhakar said: (Tue, Jan 18, 2011 03:41:30 AM) It's is very nice process to do this problem.

 Prakash said: (Sun, Jan 23, 2011 02:11:58 AM) v=d/t means velocity=distance/time

 Gokulnath said: (Sun, Jan 30, 2011 04:42:42 AM) Why se converting m/sec into km/sec?

 Sairaj said: (Thu, Feb 3, 2011 08:46:03 AM) 1 mile=1.61 km

 Hanumantha Reddy said: (Fri, Feb 4, 2011 11:54:28 PM) Hi good morning this problem am not understand please explain me.

 Reddy said: (Fri, Feb 4, 2011 11:57:39 PM) @Rita Please explain this problem I am not understand.

 Soundhar said: (Sun, Feb 20, 2011 12:31:40 AM) Let length of the train be 'x' metres... Speed of the train = 60km/hr(given) Time = 9seconds(given) refer the formulas for train problems... As the time is given in seconds and answers are given in metre(train length) we are in need to convert from km/hr to m/s km/hr = 1000m/(60min*60sec) = 5/18 m/s Length of the train(distance covered a post)= speed * time = (60*(5/18))*9 = (50/3)*9 = 150 m For the train related formulas,check the READ MORE in Left corner(Important formulas)...

 Contactjerin said: (Thu, Mar 3, 2011 03:34:20 PM) Any one know the how many feet is one meter?

 Sundar said: (Thu, Mar 3, 2011 11:50:57 PM) @Contactjerin Feet to Meter conversion: 1 feet = 0.3048 meter Meter to Feet conversion: 1 meter = 3.28083 feet This is what I mentioned already in this discussion. You can easily find the answer for your question that is: 3.28083 feet = 1 meter.

 Suganthan.M said: (Sat, Mar 12, 2011 02:33:05 AM) From the question we can predict speed= distance/hour ((by speed=60 km/hr)note the km/hr) As to calculate for 9 sec I am converting the whole things to seconds (i.e.)speed=60000/3600=16.666666(remember this is for one second) therefore for 9 seconds 16.666666*9= 150

 Vishnu said: (Tue, Mar 15, 2011 06:12:31 AM) (sqrt(3N))^3/2 = 90 How to find N value from this problem?

 Matta.Srinuvasrao said: (Sat, Apr 2, 2011 03:36:20 AM) I'M UNDERSTAND SIR BUT I'm suppose to be confusing to seeing above following questions so I'm kindly requesting you to explain the solutions above question, thank you.

 Umesh said: (Mon, Apr 4, 2011 11:54:41 AM) Hi Kalimuthu great explanation.

 Palanivel said: (Mon, Apr 25, 2011 02:15:30 AM) Hi i am palanivel i got ur explanation for above question..thak you..

 Joseph said: (Wed, Apr 27, 2011 10:59:34 PM) First convert the km into metres 60km will bcome 60000 metres then divide 60000 with 1 hour that is 60,60000/60 this will give us the speed of the train in mins n then 1000 with 60(to convert the speed in seconds)then multiply the ans with 9 seconds.ie 16.66*9 will give us 150 :)

 Nagaraju said: (Wed, May 18, 2011 12:58:01 PM) Here we have to think that they are asking the length of train. First we have conform that all the values given are same format or not . if not we have to convert them into one format depending on the answers given to us. Then it is possible to get the correct answer. The first answer explanation by Sundar is very good .

 Aradhana said: (Sun, May 29, 2011 07:53:25 AM) The first answer which was given by sunder is best, even a kid can understand it well, well done sunder.

 Dheeraj said: (Sun, May 29, 2011 01:37:55 PM) Nice trick.

 Sekhar said: (Thu, Jun 9, 2011 09:33:40 AM) The first answer is the best answer

 Ashwini said: (Fri, Jul 15, 2011 06:43:56 AM) @ Kalimuthu Thanks...I understand your solution.

 Geeth said: (Wed, Aug 3, 2011 03:20:46 PM) Just now I know the formula for converting meter to feet. Thank you. Sundar.

 Sridhar said: (Wed, Aug 10, 2011 02:16:28 PM) Can any one say me about pole in this question?

 Aditya said: (Sat, Aug 20, 2011 03:52:28 PM) Sonali invests 15% of her monthly salary in insurance policies. She spends 55% of her monthly salary in shopping and on household expenses. She saves the remaining amount of Rs. 12,750. What is Sonali's monthly income?

 Sundar said: (Wed, Aug 24, 2011 01:05:35 PM) Q. Sonali invests 15% of her monthly salary in insurance policies. She spends 55% of her monthly salary in shopping and on household expenses. She saves the remaining amount of Rs. 12,750. What is Sonali's monthly income? Solution: Let the monthly-salary be X. Total %-of-amount spent = (15 + 55) = 70% of X. Remaining amount saved is 30% of X. Now, 30% of X = 12750. Then 100% of X = ? X = (12750/30) x 100 = 42,500. Required answer X = Rs. 42,500. // Note:- Amount Spent in Insurance (15% of X) = (15/100) x 42500 = Rs. 6,375. Amount Spent in Shopping (55% of X) = (55/100) x 42500 = Rs. 23,375. Amount Saved (30% of X) = (30/100) x 42500 = Rs. 12,750. Monthly Salary = Rs. (6375 + 23375 + 12750) = Rs. 42,500.

 Jayanthi said: (Mon, Sep 5, 2011 12:35:44 AM) Lets take mnthy salry to be x; then , x-15x/100+55x/100=12750; x-14x/20=12750; 6x/20=12750; x=(12750)20/6 x=42,5000; monthly salry is Rs.42,500

 Edger said: (Mon, Sep 12, 2011 10:56:03 PM) 60*5/18 = how to calculate this logic, but I'm clear next step --50/3*9=150---guys please explan this.

 Hifzur said: (Wed, Sep 14, 2011 08:31:16 PM) Its simple no need of going that 5/18 it wil give confusion. Convert 60 km into meter i.e 60000m. Now speed is 60000m/hr... convert it into per second. i.e 60000/(60*60)=16.66 As we know length=(speed*time) :.16.66*9 = 150.

 Roshan Machhi said: (Wed, Oct 19, 2011 08:25:55 PM) I understand it but just explain in detail.

 Ghanshyam said: (Fri, Oct 21, 2011 06:07:57 PM) Nice explanation in detail. Thank you very much.

 Sara said: (Sat, Oct 22, 2011 07:03:45 AM) Distance = Time *speed 1km =1000Meteres 1hr =3600 seconds Distance = 60*9/3600 =9/60 km Distane in Metres =(9/60)*1000 =150M simple and fast way

 Fuzail Ahmad said: (Sat, Nov 12, 2011 09:41:33 PM) Very good to all.

 Jayakumar said: (Sun, Nov 13, 2011 08:09:23 PM) Jayanthi, Sundar, Kalimuthu Thanks for a lot to YOU all I can easily understand your problem solving system and it is not only useful to me but also to all thanks thanks thanks thanks thanks

 Baskar said: (Thu, Nov 17, 2011 04:24:44 PM) Any one know the how many feet is one meter? well explanations sundar.

 Ajay said: (Mon, Nov 21, 2011 10:01:10 AM) Guy's why we multiply (speed x time) to find length. train is going with 50/3 meter in one second, suppose this train passes this pole in 1 second then train length would be 50/3 meter. (because 50/3 meter is covered by 1 second) now suppose this train passes this pole in 2 second then train length would be (50/3)x 2 meter now here train passes this pole in 9 second so the train length would be (50/3) x 9 = 150 meter

 Vikram said: (Thu, Nov 24, 2011 11:19:27 AM) Here,The Train speed =60km/1hr & That Train was crosses a one Pole in 9 Seconds. So,Therefore we are converting Km into Meters And Hour into Seconds..... i.e.,That train speed=60km/60Minute. i.e.,that Train Speed=1km/1Minute. and 1km=1000meters ,1Minute=60seconds. So,The Train Length = 1Km/1Minute *9. that means ,Length of Train=(1000/60)*9. =150 Meters.

 Raja said: (Wed, Nov 30, 2011 10:42:44 AM) What is the shortcut method to calculate gcf of numbers?

 Thangaraj K. said: (Thu, Dec 15, 2011 08:24:56 AM) Answer = sec/speed*1000 (i.e. - multiplied with 1000 to convert to metres ) =9/60*1000 = 150m

 Sai said: (Sat, Dec 17, 2011 12:55:59 PM) @SAI Simply sperb

 Suresh said: (Sun, Dec 18, 2011 08:56:13 PM) Imagine the pole as a car moving on the train(road) which has a distance of 150m. If the pole(car) takes 9 sec to complete 150m, then what is the speed? speed of the pole(car)=150m/9sec = 16.67ms-1 =16.67*(18/5)km/hr =60km/hr

 Janeth said: (Mon, Feb 20, 2012 01:56:54 PM) @Jayath how about -14x/100. I do not understand. Where did you get the number?

 Thaya said: (Wed, Mar 14, 2012 12:51:30 AM) @ Kalimuthu This was a nice Explaination

 Shubham said: (Fri, Mar 30, 2012 06:53:32 PM) How did you calculate speed ?.

 Gokul said: (Tue, Apr 3, 2012 10:29:34 AM) Really nice explanation.

 Hitesh said: (Mon, Apr 9, 2012 08:18:53 AM) When I saw the explanation I was confused that why these gyes used 5/18 to multiply But now I got it. Thanks!

 Sudharsan said: (Sun, Apr 15, 2012 05:17:16 PM) Let the length of the train be x. 3600/9=6000/x. X=150m !

 Satish said: (Fri, Apr 20, 2012 07:15:07 PM) Another simple way. We have to find the length of the train (in mts). Given in km/Hr ==> 5/18 mts/sec. (1). Also given time to cross the post i.e. in Sec. Multiply 1 & sec => (mts/sec) *sec ==mts (ur answer).

 Lokesh said: (Sat, Apr 21, 2012 06:43:44 PM) Local Train Leaves from a station at an intervals of 15 mins at a speed of 16kmph. A man moving from oppsite direction meets the train at an interval of 12 min. find the speed of that man?

 Sandeep said: (Wed, Jun 6, 2012 07:00:45 PM) Firsst 60 km/sec need to be converted in to meter /second. It could be by multiply by 60*5/18 and then it multiply by 9 secound and hence anse we get 150 meter.

 Kusuma said: (Wed, Jul 4, 2012 03:08:42 PM) In simple way, time/time = length/length. Here we convert the 1 hour into seconds and the given time is 9 seconds. We convert the kilo meters into meters then we can easily solve it. 3600/9 = 6000/x. X = 150m.

 Talada Sandeep said: (Sat, Jul 21, 2012 01:19:25 PM) Since time is given in seconds , sure you have to convert velocity of train in units of m/sec Since 1 km = 1000 m and 1 hr =60 m = 60*60 sec, According to question,speed 60 km/hr = 60 * (1000/3600) = 50/3 m/sec, time = 9 sec We know that , distance=speed*time, therefore length = (50/3)*9 =150 m.

 Rakshith Devraj said: (Tue, Jul 24, 2012 09:28:06 PM) Guys check this out. ! This comment is to make you understand conversion of km/hr to m/s by using easy method. , Observe carefully conversion of km/hr to m/s. , 12*1=12. 12*2=24. 12*3=36. 12*4=48. 12*5=60. For any number (which has to be converted to m/s from km/hr) coming as the result (r) of multiplication table of 12. , you can easily write it as (quotient*10) /3 m/s. , Example:- 60km/hr = 50/3 m/s.

 Ashik said: (Thu, Aug 2, 2012 10:47:53 AM) Dear Friends. The problem is really nice ans soothing. I solved it firstly but when I saw the solution, I confused to see the calculation. After a deep concern and explanation I think it really a nice explanation. Okay friends after that thank to Sundar for posting another problem and solution. Thank to Kartik, Dhessappan, Jain Thomas, Rita, Valimithu, Jayanthi, Vishnu, Poonm, poja, Sunny, Sara and others.

 Divya said: (Sun, Aug 19, 2012 09:29:06 PM) Salary problem Let's take salary amount as X. she spends 15% of X on policy=15X/100 55% of X on shopping &house expe=55X/100 rem of salary=12750 so,X-(15X/100)-(55X/100)=12750 30X=1275000 X=42500

 Prashantkumar Nigadi said: (Tue, Aug 28, 2012 02:55:41 PM) We know that 1km=1000meters 1hr=3600seconds 1km/1hr=1000/3600=10/36=5/18m/s 1km/hr=5/18m/s 60km/hr=(60*5/18)

 Bangaru said: (Wed, Sep 26, 2012 08:04:32 PM) @Divya. Can you explain the problem which was mentioned by you ?

 Srikanth said: (Tue, Oct 2, 2012 11:53:15 AM) Can you explain the problem with diagrammatic representation ?

 Anil said: (Tue, Oct 9, 2012 01:40:14 PM) @Bangaru. If the total salary is 100%, in which 15% spent on insurance policy means 100-15 =85%. 55% spent as expenditure on shopping etc means 85-55 =30% Savings =salary -expenditure. 30% savings equals to 12,750. Percentage can be represented as per hundred i.e., 30/100, which is equals to 12,750. Assume that total salary be X X *30/100 =12,750 X =12750*100/30 X= 42500.

 Manoranjan Samal said: (Mon, Oct 29, 2012 03:09:52 PM) Let length of the train be 'x' metres... Speed of the train = 60km/hr(given) Time = 9seconds(given) Refer the formulas for train problems... As the time is given in seconds and answers are given in metre(train length) We are in need to convert from km/hr to m/s km/hr = 1000m/(60min*60sec) = 5/18 m/s Length of the train(distance covered a post)= speed * time = (60*(5/18))*9 = (50/3)*9 = 150 m For the train related formulas,check the READ MORE in Left corner(Important formulas)...

 Srinu said: (Tue, Dec 4, 2012 03:56:43 AM) We know that 1km=1000meters 1hr=3600seconds 1km/1hr=1000/3600=10/36=5/18m/s 1km/hr=5/18m/s 60km/hr=(60*5/18).

 Jagadeesh said: (Mon, Dec 31, 2012 11:48:45 AM) Here, give train travels at a speed of (60*5/18) m/s, that is for one second it travels a distance of 50/3 m/s. So the distance traveled for 9 seconds gives the actual length of train, that is 50/3*9=150m.

 Kishan said: (Mon, Jan 7, 2013 09:36:13 AM) Similarly, Speed = [60*5/18]m/sec=50/3 m/sec. 50/3*9 = 150mtrs.

 Raj said: (Thu, Jan 17, 2013 09:24:12 PM) Speed = [60*5/18]m/sec=50/3 m/sec. 50/3*9 = 150mtrs.

 Rasu said: (Mon, Jan 28, 2013 03:48:39 PM) Speed convert km/h to m/sec speed=[60*5/18]m/sec speed=[50/3]m/sec. Distance=[speed*time] Length of the train=[50/3*9] =150m.

 Santosh, Aps, Goregaon said: (Thu, Feb 7, 2013 05:20:29 PM) Total exp= 15%+55%= 70% Let salary rs.100 Save= 100-70= Rs.30% Rs.30%= 12750. 100% = 12750/30x100=42500.

 Udai said: (Sun, Mar 3, 2013 01:59:06 PM) How to convert m/sec in to km/hour?

 Hari Prasath said: (Wed, Mar 20, 2013 10:24:13 PM) How to convert feet into meter?

 Ranjeet_Great said: (Tue, Mar 26, 2013 02:32:02 PM) @Udai. Its very easy to convert m/sec in to km/hour, Just multiply 18/5. For example if we want to convert 5meter/sec in to km/sec then we will convert meter into km and sec in to hour. That is 5meter=(5/1000)km and 1sec=(1/3600)hour. So 5m/sec={(5/1000)/(1/3600)} km/hour. or (5*3600)/(1*1000) km/hour or (5*36)/(10) km /hour or (5*18)/(5) km/hour or 5 km/hour.

 Anbu said: (Tue, Apr 30, 2013 11:24:29 AM) How to calculate percentage(%) in marketing?