Aptitude - Time and Distance - Discussion
Discussion Forum : Time and Distance - General Questions (Q.No. 2)
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:
hours, it must travel at a speed of:Answer: Option
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 |
Discussion:
160 comments Page 15 of 16.
Nikita said:
1 decade ago
Another way
This is an example of inverse variation
So,
240*5=5/3*x
x=720
This is an example of inverse variation
So,
240*5=5/3*x
x=720
Lakhan said:
1 decade ago
I have not understood the step where you have taken 1200*3/5 instead of 1200*5/3 ?
Sreenath said:
1 decade ago
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.
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.
Avinash said:
1 decade ago
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
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
(3)
Ramkumar said:
1 decade ago
Sir/madam please explain in detail. I cant understand.
Sheela m b said:
1 decade ago
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.
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.
Rahul said:
1 decade ago
Please explain in detail the calculation of coverting to 5/3
Selva said:
1 decade ago
Nice example.
Darshan said:
1 decade ago
Aeroplane travels total of 1200km to cover same distance in 1 hour it should travel wit 1200 kmph right but how come 720 kmph ?
Neelam said:
1 decade ago
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.
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