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Aptitude - Time and Distance - Discussion

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"Nothing is impossible to a willing heart."
- (Proverb)
2.

An aeroplane covers a certain distance at a speed of 240 kmph in 5 hours. To cover the same distance in 1 hours, it must travel at a speed of:

 [A]. 300 kmph [B]. 360 kmph [C]. 600 kmph [D]. 720 kmph

Explanation:

Distance = (240 x 5) = 1200 km.

Speed = Distance/Time

Speed = 1200/(5/3) km/hr.     [We can write 1 hours as 5/3 hours]

 Required speed = 1200 x 3 km/hr = 720 km/hr. 5

 Vino said: (Sun, Jul 11, 2010 02:01:20 AM) How to give 3/5 ?

 Mohit said: (Sun, Jul 18, 2010 09:31:15 AM) It is (3*1)+2=5 So it 5/3 hours and now speed = distance/time that's why 3/5.

 Srinivasan.S said: (Mon, Aug 23, 2010 09:46:05 AM) The distance wants cover with 1+(2/3)hour is 1200km. 1 + (2/3) = (3+2)/3 = 5/3. speed=Distance/time speed=1200km/(5/3) speed=1200km*(3/5) speed=720km/hr

 Shwetha Shree said: (Mon, Sep 6, 2010 01:08:32 PM) D= S*T that's why 240 * 5.

 Sree said: (Thu, Sep 23, 2010 10:56:59 AM) Hello! Shwetha, You want to take it as comparison of two plan. First Plan : 240km * 5hr = 1200km/hr Second Plan: ? *1+(2/3)= 1200km/hr

 Pandu said: (Wed, Dec 22, 2010 09:20:08 AM) How to give 3/5?

 Ankit said: (Thu, Dec 23, 2010 03:28:26 PM) Correct mohit. !

 Ramya said: (Mon, Jan 24, 2011 02:35:02 AM) Distance=240*5=1200 1+2/3=5/3 REQUIRED SPEED=(1200/5/3) =(1200*3/5) =720KM/HR

 M.Balaji said: (Sat, Jan 29, 2011 06:48:53 AM) d1=d2 240*5=x*(5/3) 3600=x*5 x=720(km/hr) If both are available in kmphr other we convert them as same. It is very useful to students. I like this site.

 V P Samy said: (Sun, Jan 30, 2011 07:29:26 AM) I have doubt in 5/3. 5*240=1200km 1*(sp)=1200km .'.Speed=1200km/hr this is correct or not ?

 Neelam said: (Thu, Feb 3, 2011 02:28:18 AM) Actually this is not speed, it must be the distance. As it is derived from the formula s*t=d. Hope it clears the confusion.

 Darshan said: (Thu, Feb 10, 2011 06:18:00 AM) Aeroplane travels total of 1200km to cover same distance in 1 hour it should travel wit 1200 kmph right but how come 720 kmph ?

 Selva said: (Fri, Feb 25, 2011 06:33:39 AM) Nice example.

 Rahul said: (Tue, Mar 1, 2011 01:40:05 PM) Please explain in detail the calculation of coverting to 5/3

 Sheela M B said: (Mon, Mar 28, 2011 03:42:33 PM) observe the formula carefully. Distance = (240 x 5) = 1200 km. Speed = Distance/Time it says speed equals distance travelled by time taken and hence, Speed = 1200/(5/3) km/hr. since time is 5/3, the denominator(here it is 3) of denominator(the whole 5/3)becomes numerator. Therefore the following. Required speed = 1200 x 3 km/hr = 720 km/hr.

 Ramkumar said: (Thu, May 19, 2011 01:35:42 AM) Sir/madam please explain in detail. I cant understand.

 Avinash said: (Sun, May 22, 2011 08:57:44 AM) Ramkumar,nothng hard in tat.first knw formula distance=speed*time speed=distance/time time=speed/distance now read the question.they given aeroplance covers distance of 240 km/hr in 5 hours so we need the total distance of 5 hours... distance=speed*time so distance=240*5=1200km now we have to speed cover in 1+2/3 hours=5/3 hours speed=distance/time speed=(1200/5/3)kmph=(1200*3/5)kmph=720 kmph

 Sreenath said: (Sat, Jul 9, 2011 12:04:30 PM) Hi, we know that speed=distance/time Here distance is constant for different times so speed o< 1/time i.e s1/s2=t2/t1 => s2=s1*(t1/t2) => s2=240*[5/(5/3)] => s2=240*3 => s2=720 here s2 is the speed when time is 5/3 remember when distance is constant speed o< 1/time if speed constant time o< distance if time is constant speed o< distance Thanks.

 Lakhan said: (Tue, Aug 2, 2011 03:26:35 PM) I have not understood the step where you have taken 1200*3/5 instead of 1200*5/3 ?

 Nikita said: (Mon, Aug 8, 2011 12:47:31 PM) Another way This is an example of inverse variation So, 240*5=5/3*x x=720

 Honey said: (Fri, Aug 19, 2011 08:06:37 PM) Time decrease by 3times. 5/3=1*2/3. Therefore speed increases by 3 times=3x240=720km/hr.

 Dilip said: (Thu, Oct 20, 2011 06:25:56 PM) Those who says Answer as 720 please read the question. Its given that speed for a time of 1Hr should be foun out, not for 1+ (2/3) hrs.

 Joseph said: (Sat, Dec 17, 2011 10:25:47 AM) Even if the aeroplane travels in the speed of 720km/hr it can the distance of 1152km..... As the nearest answer is 720km/hr.

 Josh Koikkara said: (Wed, Aug 15, 2012 11:03:22 AM) Speed: 240Km/Hr Time: 5Hrs Distance= Speed*Time D= 240*5 =1200m Given, Time=5/3Hr Speed= Distance/Time = 1200/(5/3) = 1200*3/5 =720 Km/Hr

 Nil said: (Sat, Aug 18, 2012 03:36:09 PM) Those who says answer as 720, why you are taken time as 5/3 hr instead of 1 hr as given in d example.

 Abhishek Sunny said: (Tue, Aug 28, 2012 09:27:18 AM) Those who says the answer is 720kmph please concentrate on my statement----. If the answer is 720kmph then it means if we multi 720kmph with the given time of 1hr then we get the this which is 1200km isn't. But did we get it?!

 Pramoth said: (Tue, Oct 30, 2012 11:24:11 PM) Here the speed is given in Km/hr and time in hours, why the hours are not converted into mins ?

 Satheesh M said: (Tue, Dec 18, 2012 06:55:35 PM) 240 Km/hr in 5 hours 5X60=300min in 1 2/3 hrs to travel the same distance 1 2/3X60=100 =240/100X300=720

 Roxy said: (Tue, Jan 22, 2013 11:52:07 PM) There are 3 speeds 12m, 14m and 16m covering equal distance. What is the average speed? please solve it.

 Swaroopmohan said: (Sun, Feb 3, 2013 08:13:42 PM) How can you write 1 hour as 5/3 hours?

 Raju said: (Thu, Mar 14, 2013 11:23:24 PM) @vino that speed 1200/(5/3) this term converted (1200*3)/5.