Aptitude - Time and Distance - Discussion

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

Answer: Option D

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: (Jul 11, 2010)  
How to give 3/5 ?

Mohit said: (Jul 18, 2010)  
It is (3*1)+2=5

So it 5/3 hours and now speed = distance/time that's why 3/5.

Srinivasan.S said: (Aug 23, 2010)  
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: (Sep 6, 2010)  
D= S*T that's why 240 * 5.

Sree said: (Sep 23, 2010)  
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: (Dec 22, 2010)  
How to give 3/5?

Ankit said: (Dec 23, 2010)  
Correct mohit. !

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

M.Balaji said: (Jan 29, 2011)  
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: (Jan 30, 2011)  
I have doubt in 5/3.
5*240=1200km
1*(sp)=1200km

.'.Speed=1200km/hr this is correct or not ?

Neelam said: (Feb 3, 2011)  
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: (Feb 10, 2011)  
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: (Feb 25, 2011)  
Nice example.

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

Sheela M B said: (Mar 28, 2011)  
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: (May 19, 2011)  
Sir/madam please explain in detail. I cant understand.

Avinash said: (May 22, 2011)  
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: (Jul 9, 2011)  
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: (Aug 2, 2011)  
I have not understood the step where you have taken 1200*3/5 instead of 1200*5/3 ?

Nikita said: (Aug 8, 2011)  
Another way

This is an example of inverse variation

So,
240*5=5/3*x
x=720

Honey said: (Aug 19, 2011)  
Time decrease by 3times. 5/3=1*2/3.

Therefore speed increases by 3 times=3x240=720km/hr.

Dilip said: (Oct 20, 2011)  
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: (Dec 17, 2011)  
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: (Aug 15, 2012)  
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: (Aug 18, 2012)  
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: (Aug 28, 2012)  
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: (Oct 30, 2012)  
Here the speed is given in Km/hr and time in hours, why the hours are not converted into mins ?

Satheesh M said: (Dec 18, 2012)  
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: (Jan 22, 2013)  
There are 3 speeds 12m, 14m and 16m covering equal distance. What is the average speed? please solve it.

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

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

Arjun said: (May 30, 2013)  
Please explain in detail how it converts 1(2/3) hrs into 5/3hrs?

Ruchi said: (Jul 3, 2013)  
Please explain me 5/3 hrs. How it converts?

Mona said: (Jul 7, 2013)  
1 2/3 is a mixed-fraction so 1st we have to multiply denominator with which is in-front of fraction & add it to numerator then we will get a 5/3.

Payal Gupta said: (Jul 13, 2013)  
Distance = (240*5) = 1200km.

Speed = Distance/Time.

Speed = 1200/(5/3) km/hr.

= 1200*3/5.

= 720 km.

Sudharsan Madurai said: (Aug 9, 2013)  
1(2/3) = 1.66.

5 hours/1.66hours *240 km/ph = 720 km/ph.

Govindraj said: (Sep 23, 2013)  
Shortcut:

Because Distance traveled by Aeroplane is Same with different speed.

If speed ratio is "a:b" then time ratio will be "b:a" for same distance. So,

240:x = (5/3) :5 here 1 to the 2/3 = 5/3.

240:x = 1/3.

x = 240*3 = 720.

Rosy said: (Oct 11, 2013)  
Hi friends, here in question they given as time for 1 hr, but all you guys taking as 5/3, why?

Rajesh said: (Oct 14, 2013)  
Total distance covered in 5 hrs = (240*5) = 1200 kms.

We have to cover 1200 kms in 1(2/3)hrs, which is 100 min.

Therefore for 1 min we should cover (1200/100) = 12 kms.

For 60 min(1hr) = (12*60) = 720.

Sukumar said: (Feb 1, 2014)  
By dividing 3/5 why I am not getting 0.6 how to do it?

Veeresh said: (Apr 25, 2014)  
Why we should write 5/3 as 3/5?

Vijay said: (Apr 30, 2014)  
Speed = distance/time.

Distance = same.
Speed S1 = 240, Speed S2=?
Time t1 = 5hours, time t2 = 3/5hours.

S1/S2 = t2*t1.
240/S2 = (3/5)/5.
S2 = 720 kmph.

Vinayaga said: (May 19, 2014)  
Why we use 1+2/3 ?

Udaya said: (May 30, 2014)  
This can also be solved as:

Given d1 = d2.

=> s1*t1 = s2*t2.
240*5 = s2*5/3.

s2 = 240*5*3/5.
s2 = 720 kmph.

Jeeva said: (Jul 9, 2014)  
240km--------5hr.
? --------5/3hr.

240*5/5/3 the 5/3 become 3/5 when it come up, the 5 can cut.
So finally we can 240*3 = 720kmph.

Jabi Mir said: (Aug 19, 2014)  
Here, V1 = 240 km/h, T1 = 5 h, Also, V2= ?, T2 = 5/3.

We Know, V=S/T or S = VxT, But here distance is same,
Therefore, V1xT1=V2xT2, rearranging we get, V2 = V1xT1/T2.

Substituting values,
V2 = 240 x 5 / 5/3 or we can write it, V2 = 240 x 5 x 3/5.

On simplifying we get, V2=720 Km/h.

Manasa said: (Aug 26, 2014)  
1 hr become 5/3hr as:

1 hr is 1/3 rd of part in 5hrs that means 1 = 3/3.
1 = (5-2)/3, 1 = (5/3)-(2/3), 1+(2/3) = 5/3,

Then 5/3 = 5/3.

Here it is proved 1hr is 1/3rd of part in 5hrs.

Divyan said: (Aug 27, 2014)  
Why we are multiplying 240*5?

Because they 5hrs right. So it has to be 5*3600 right.

Veerapandi E said: (Sep 28, 2014)  
How come 5/3?

Dhanshri said: (Oct 16, 2014)  
s = d/t.

s1 = d1/t1.

s2 = d2/t2.

s1t1 = s2t2/distance is same.

t2 = s1t1/s2.

t2 = 240*5/(5/3).

t2 = 720.

Bhupesh Shahare said: (Oct 28, 2014)  
Still it confusing, how 5/3 comes?

Sai said: (Nov 10, 2014)  
1200/5/3

= 1200*3/5 = 3600/5 = ?

Manoj said: (Nov 16, 2014)  
Why distance is 3?

Gloria said: (Nov 16, 2014)  
Please more explanation on 5/3?

Penny said: (Nov 22, 2014)  
Either the options are incorrect or there is something seriously wrong with my basics.

How could 1 hour be written as 5/3?:-o.

Nama said: (Jan 8, 2015)  
= (1+2/3).
= (3+2/3).
= (5/3).

Deepak Roy said: (Jan 30, 2015)  
Why you taken 1+2/3?

Chitaranjan Bhoi said: (Mar 11, 2015)  
If it cover 1200 km in one hour then its speed is 1200 km/hr. How it is 720 km/hr?

Suchi said: (Jun 3, 2015)  
Why this is wrong?

Speed = 240 km/hr.
Time = 5 hrs.
Distance = 240*5 = 1200 km.

Which means for 1 hr its 240 km. So for 5/3 hr it is 5/3 *240 = 400 km.

Manoj said: (Jun 13, 2015)  
Please explain the second line.

Nisha said: (Jun 16, 2015)  
Why 1 hr is 5/3 solve please in easy way.

Michi Tara said: (Jun 25, 2015)  
How 1hr is written as 5/3 please explain me?

Rashmi said: (Jul 8, 2015)  
Hi it's not 1 hr. The question is very clear. It is 1 2/3 hrs.

1 2/3 is in mixed fraction. To know more about converting mixed fraction you have @Mona's reply in the forum.

Vaibhav said: (Jul 16, 2015)  
When distance is same. At that time use the following formula.

v1t1= v2t2.

We have:

v1=240.
t1=5.
t2=5/3.

Therefore we easily find out v2 =720.

Vaibhav said: (Jul 16, 2015)  
Use the simple formula to solve such type example.

v1t1 = v2t2t.

Vignesh said: (Aug 3, 2015)  
Friends problem is in question sometime it shows 1 hrs and sometimes 1 2/3 hrs.

Chandra Bhushan said: (Aug 9, 2015)  
An aeroplane leaves late by 30 minutes. It has to cover a distance of 1200Km. The pilot has to increase its speed by 200Km/Hr to reach its destination on time. Find out the original speed of the aeroplane.

Julius said: (Aug 31, 2015)  
I got the point of 5/3 but I don't get how it becomes 3/5?

Aishu said: (Sep 3, 2015)  
Exactly even I dint get how 3/5 can anyone tell?

Vimo said: (Sep 19, 2015)  
How to get 3/5?

Naren said: (Oct 29, 2015)  
Here they wrote fraction 5/3 as mixed numbers (1 2/3).

Let me explain how to write it.

Here, the whole number is 1.

The denominator is 3 and the numerator is 2.

I) 1st Multiply the whole number by the denominator. i.e. 3*1=3.

II) Add the result to the numerator: i.e 3+2=5.

III) Now The numerator is 5. The denominator remains 3. --> so 5/3.

We got the output.

Raptor said: (Nov 14, 2015)  
In the question I read it as to find the speed to cover the same distance in 1 hour (not as 1 2/3).

Either I read is right or all others read it wrong, I got the answer 1200kmph.

My logic is, since the total distance calculated is 1200 km, and in one hour it should cover the same distance, my answer is right.

Ashok Kumar Parida said: (Dec 31, 2015)  
Distance = (240*5) = 1200 km.

S = D/T.

Speed = 1200/(5/3) km/hr.

My question where come from (5/3)?

Deepak said: (Jan 20, 2016)  
Distance = 240, 5 hour.

To cover same distance = x, 5/3 hour.

1 hour = 60 minutes, 5 hour = 300 minutes, 5/3 hour = 100 minutes.

= (5/3*60 minutes = 100 minutes).

= 240*300 = x*100.

72000 = x*100.

x = 72000/100.

x = 720.

So speed is 720 kmph.

Pooja said: (Feb 8, 2016)  
Not satisfied, still confuse why we are taking 5/3 as time why not 1? Please explain it well?

Vaitheesh Kumar said: (Feb 17, 2016)  
2 + 3 = 5*1 = 5.

It is in fraction that is why should write need write in fraction form so 5/3.

Namrata Bajpai said: (Mar 30, 2016)  
A/Q as the distance is same.
So, d1 = d2.
We know that D = S/T.
So, S1 * T1 = S2 * T2 ----> (1).
Already, we have the value of s1= 240, t1 = 5, s2 = ?, t2 = 5/3.
So, according to the equation 1, we get S2 = 720.

Bdboy Hasan said: (May 2, 2016)  
Previous time is 5 * 60 = 300 minute and new time is 60 + 40 = 100 minute.
So, we need to increase speed 3 times as our required time is reduced 3 times.

So the speed will be 240 * 3 = 720 kmph.

Mayur said: (May 7, 2016)  
Why we convert 5/3 into 3/5?

Please tell me.

Sumit Wanza said: (Jul 20, 2016)  
240 km hour in 5 hours so 240 * 5 = 1200 km total distance.

Distance = 1 + 2/5 = 3/5.
= 1200/1 * 3/5.
= 1200 * 3 = 3600, = 1 * 5 = 5 .
= 3600/5 = 720.

So, the answer is 720 km.

Omar Faruq said: (Jul 29, 2016)  
I think the question should be in 1 hour 40 minutes not in 1 hour.

Naresh said: (Aug 4, 2016)  
@Manasa explain is clear please visit it.

Hiyaaa said: (Oct 11, 2016)  
How do you divide 1200 by 5/3? I need a reference.

Vishal said: (Oct 17, 2016)  
Nice explanation thanks @Avinash.

Minerve Baruah said: (Nov 25, 2016)  
A car moves a distance of 450 km in 8 hours find its speed?

Solve and explain the answer.

Gokul said: (Nov 25, 2016)  
How 5/3 changed into 3/5? Please tell.

Ross said: (Nov 27, 2016)  
Why does the 5/3 change to 3/5?

Bharath said: (Dec 17, 2016)  
If a boy walks at a speed of 12kmph, he takes 20 min to reach school. If he has to reach in 15 min, then with what speed he should walk?

Please tell me the solution.

Jayalakshmi said: (Dec 29, 2016)  
Distance= s * t so 12 * 20 = 240,
Spd = d/t.
t = 15.
Distance = d/t
= 240/15 = You will get the Answer.

Velu said: (Jan 17, 2017)  
Speed ---- time
240 ---- 5
x ---- 5/3...

In direct proposal.
240 * 5 * 3
----------------
5
= 740 km/hr.

Swarup said: (Jan 18, 2017)  
Actually, I can't understand that why we put distance=1200 km/hr and how?

Akhil Reddy said: (Feb 3, 2017)  
I can solve in this way without formulae.

1.2/3 = 1.66.
240 km 5hrs.
Ans :-
5/1.66 = 3.0
So, 240 (3) = 720kmph.

Anisha said: (Apr 5, 2017)  
Aeroplane travels total of 1200km to cover same distance in 1 hour it should travel wit 1200 kmph right but how come 720 kmph?

I want the explanation.

Ruchi said: (May 25, 2017)  
In the question, time is 1 2/3 hours, not one hour so we take it as 5/3 and get the answer as 720.

Dev said: (Jun 12, 2017)  
What is the formula of distance? Please tell me.

Sudha said: (Jul 1, 2017)  
Speed=distance÷time.

So, we substuite those values.

S = 1200/5/3.but why should change 5/3 as3/5.please tell me, I get confused.

Satish said: (Jul 12, 2017)  
Why we do 5/3 and question is for 1 hour?

Why everyone doing fraction, it is just simply asked how much speed in 1 hour if some purpose is there for doing 5/3 then explain me.

Pradeep said: (Aug 27, 2017)  
@Sudha, @Satish.

S = 1200/5/3 is correct.
S = 1200*3/5 just for calculation 3is multiplied with 1200.

Arjun said: (Jan 25, 2018)  
distance const d=c ,here s1t1=s2t2.

240*5÷5÷3=720kmph.

Niv said: (Feb 20, 2018)  
Why should we convert 5/3 to 3/5?

Please anyone explain me.

Vatsalya said: (Mar 1, 2018)  
Here 1+2/3=5/3.

It was given that speed=dis/time,
so, speed= 1200/(5/3),
=1200*3/5,
=720kmph.

Vishwanath said: (Apr 23, 2018)  
Guys, it was 1+2/3, not 1x2/3.

Aaqib said: (May 19, 2018)  
And it's not 1+2/3, it is 1*2/3 which means 1 hour and 2/3 minutes.
1*2/3 evaluates to (3*1+2)/3=5/3 hrs.

Prabakaran said: (Jul 18, 2018)  
On the first, the trail the aeroplane cross the distance in 5 hours at the speed of 240 km/hr.

For the same distance in 1(2/3) hours to resolve this cross multiplication (3*1*2-3= 3 hr).
So we have to multiply 240*3 to get the value of second trail speed is 720 km/hr.

Sowmya said: (Aug 1, 2018)  
They said 1 hr. Why are you considering 1 (2/3)?

Sri Harsha said: (Aug 25, 2018)  
Fundamenta Formula : D=S*T.

Here.

S=240 kmph, T=3 hrs we can find D=240*5=1200.
To find S, S =D/T i.e. (1200*3) /5=720kmph.

Kiran Chavan said: (Aug 28, 2018)  
Keep it simple.

The distance = speed * time.
Therefore let speed be x now compare.
240*5=5/3*x.
240*5*3=5*x.
x=240*3.
x=720.

Hari said: (Sep 12, 2018)  
Speed = Distance/Time.
= 1200 ÷ 5/3,
= 1200X3/5,
= 3600/5,
= 720.

Neha said: (Sep 29, 2018)  
How come 5/3 here? Please tell me.

Sujatha said: (Jan 3, 2019)  
1(2/3)is written as 1+(2/3)=(3*1+2)/3=(3+2)/3=5/3.
now we solve s=d/t,
S=1200/(5/3),
S=1200*3/5,
S=720.

Avigeh said: (Jan 20, 2019)  
Given that->d=240kmph*5h = 1200,
t=3+2/3=5/3.
s=d/t.
s=1200/(5/3)=1200*3/5=7200.

Mukesh said: (Feb 21, 2019)  
Yes, it is 7200. Right @Avigeh.

Shashank said: (Nov 15, 2019)  
We can calculate like below right?
Per hour 240 KM & for 5 hour, 1200KM.
1200/1.666 = 720.
Is that right?

Sreedevi said: (Dec 24, 2019)  
How 1 hr equals to 1+(2/3)?

Sandhyarani said: (Feb 24, 2020)  
If we don't know basic formulas, no way to solve problem ah?

Gayathri said: (Apr 2, 2020)  
1*2/3 is a mixed fraction, we are converting it into improper fraction as 5/3.
S=d/t=1200/(5/3)=1200*3/5=720.

Naveen Kumar Reddy Gandluru said: (Apr 23, 2020)  
Distance is constant.

s1/S2=t2/t1.
240/S2=(5/3)/5.
S2=720kmph.

Harishree.A said: (Jun 11, 2020)  
D=S*T.
=240*5,
=1200 km/hr.
1 2/3 hrs can be written as 5/3hrs.

Considering the formula:

D = S*T.
1200 = x*5/3(Keeping the unknown speed as x),
1200*3/5 = x,
720 = x,
= 720km/hr.

R Ravi Kiran said: (Jun 17, 2020)  
At first, they given plane covers 240km in 5hours.

Which means 48 km per hours right?

Samir Mendhe said: (Oct 10, 2020)  
Distance= S * T.
Given 240km/hr in 5hr.
So,1hr =240 km.
then 5hr ---> 5*240 = 1200 km.

Now to cover distance 1200km in 5/3hr.
So, you can apply speed formula and the answer will 720 km/hr.

Saran said: (Jan 19, 2021)  
Distance= 240x5= 1200km.

speed = distance/ time.
=1200/(5/3).
=(1200 x 3)/5,
=3600/5,
=720km/h.

Siddhesh said: (Mar 15, 2021)  
Can you tell me 5/3 means how many minutes?

Ajai said: (Jun 15, 2021)  
Speed = distance /time methods is used here.

Vaidik said: (Jul 4, 2021)  
According to the tri-rashi method.

5hours ----------->240km/h.
5/3hours ---------> (?).

5 x 240/5 x3 =80kmph.

I know this is wrong but speed should increase here because time is decreasing but I want to know why this method is not applicable here. Please can anyone help me to solve this?

Lokesh said: (Jul 8, 2021)  
Distance = 240 * 5=1200
1 +2 /3 = 5/3.

REQUIRED SPEED = (1200/5/3)
= (1200 * 3/5)
= 720KM/HR.

Aditi said: (Aug 20, 2021)  
Why 240 x 5?

Lath ... said: (Sep 3, 2021)  
Speed 1=240kmph, time1 = 5hr.
Speed2=x. Time2=5/3.

S1/S2 = T2/T1,
S2 = (240*5)/(5/3),
S2 = 240*3,
S2 = 720kmph.

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