Aptitude - Time and Distance - Discussion
Discussion Forum : Time and Distance - General Questions (Q.No. 6)
6.
In a flight of 600 km, an aircraft was slowed down due to bad weather. Its average speed for the trip was reduced by 200 km/hr and the time of flight increased by 30 minutes. The duration of the flight is:
Answer: Option
Explanation:
Let the duration of the flight be x hours.
| Then, | 600 | - | 600 | = 200 |
| x | x + (1/2) |
 |
600 | - | 1200 | = 200 |
| x | 2x + 1 |
x(2x + 1) = 3
2x2 + x - 3 = 0
(2x + 3)(x - 1) = 0
x = 1 hr. [neglecting the -ve value of x]
Discussion:
206 comments Page 16 of 21.
Pankaj Mishra said:
1 decade ago
@Sakshi.
2 mistakes done by you.
1. D= s*T , and you have taken d=s/t as 200 Kmph is speed.
2. How 200 kmph *200 = 1200? it should be 12000. The whole logic is wrong.
2 mistakes done by you.
1. D= s*T , and you have taken d=s/t as 200 Kmph is speed.
2. How 200 kmph *200 = 1200? it should be 12000. The whole logic is wrong.
Srinath said:
1 decade ago
Generally time taken to travel 600 km with 200 kmph will take 3 hr journey but how the time of flight will be 1 hr.
Sakshi said:
1 decade ago
Distance = 600 km.
Average speed = 200 km.
If time taken is x min therefore the increased value of time = (x+30)min = (x+30)/60 hrs.
So by applying the formula of speed i.e. S=D/T, we get,
600 km=200 kmph/((x+30)/60)hrs.
600km = 200kmph*60/(x+30).
(600x+ 1800)km = 1200kmph.
Now by leaving the units as they are hrs for time , we get,
600x= 1200-1800.
600x = -600.
x = -600/600.
x = -1.
Since time can never be negative, Therefore by leaving the negative sign we get, x=1 hr.
Average speed = 200 km.
If time taken is x min therefore the increased value of time = (x+30)min = (x+30)/60 hrs.
So by applying the formula of speed i.e. S=D/T, we get,
600 km=200 kmph/((x+30)/60)hrs.
600km = 200kmph*60/(x+30).
(600x+ 1800)km = 1200kmph.
Now by leaving the units as they are hrs for time , we get,
600x= 1200-1800.
600x = -600.
x = -600/600.
x = -1.
Since time can never be negative, Therefore by leaving the negative sign we get, x=1 hr.
Ayesha said:
1 decade ago
Still confuse about 600/x-600/(x+1/2) = 200. Please let me know something very simply.
Alokpal said:
1 decade ago
Time = distance / speed.
600 *30 /200.
30 * 3 = 90 total time.
Exact time = total time - increase time.
= 90 - 30.
= 60.
600 *30 /200.
30 * 3 = 90 total time.
Exact time = total time - increase time.
= 90 - 30.
= 60.
Racer said:
1 decade ago
@ISHAN the speed of the car is 60km/hr.
1)Let the speed be x km/hr.
2)Given distance covers =420km we know time t= distance/speed.
3)So let t= 420/x.
4)Given if speed is 10km/hr more so time (t-1)= 420/(x+10).
We have considered t=t-1 above because they have mentioned 1hr less so 420/x - 420/(x+10)=(t-t-1) i.e total distance/totalspeed = time
5)By solving we get x^2+10x-4200=0 we get x=60 &-70 ignore -70... 60 is answer.
1)Let the speed be x km/hr.
2)Given distance covers =420km we know time t= distance/speed.
3)So let t= 420/x.
4)Given if speed is 10km/hr more so time (t-1)= 420/(x+10).
We have considered t=t-1 above because they have mentioned 1hr less so 420/x - 420/(x+10)=(t-t-1) i.e total distance/totalspeed = time
5)By solving we get x^2+10x-4200=0 we get x=60 &-70 ignore -70... 60 is answer.
Karthilk said:
1 decade ago
A car travelling with of its actual speed covers 42 km in 1 hr 40 min 48 sec. Find the actual speed of the car?
Ishan said:
1 decade ago
A car covers a distance of 420 km at a certain speed. If its speed is 10 km/hr more, it will take one hour less to cover the same distance. What is its speed?
Please help me?
Please help me?
Muhammad Umair Kabir said:
1 decade ago
Let Speed is X and Time is Y,
According to formula
X = 600 / Y
From question avg Speed reduced and Time taken increased eq. becomes...
X - 200 = 600 / (Y + 1/2)
put the value of X in above eq.
600 / Y - 200 = 600 / (Y + 1/2)
Simplifying the eq. we get
(Y - 1)(2Y + 3 )...
Y = 1 Ans as time is always positive....
According to formula
X = 600 / Y
From question avg Speed reduced and Time taken increased eq. becomes...
X - 200 = 600 / (Y + 1/2)
put the value of X in above eq.
600 / Y - 200 = 600 / (Y + 1/2)
Simplifying the eq. we get
(Y - 1)(2Y + 3 )...
Y = 1 Ans as time is always positive....
Babita said:
1 decade ago
@Manik , Sunita ,
200 = 600/x+30
200(x+30)=600
200x+6000=600
200x=600-6000
200x=5400
x=5400/200
x=27
200 = 600/x+30
200(x+30)=600
200x+6000=600
200x=600-6000
200x=5400
x=5400/200
x=27
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