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:
205 comments Page 5 of 21.
Jay said:
1 decade ago
Here A Shortcut method.
Initial speed = 600km/hr = s1.
Final Speed = 600-200 = 400km/hr = s2.
So, (Taking ratio of speed),
s1 : s2 = 600 : 400= 3 : 2.
So, time taken,
t1 : t2 = 2 : 3 (time and speed inversely proportional).
1 part time= 30 min.
So t1= 2*30 = 60 min = 1hr.
Initial speed = 600km/hr = s1.
Final Speed = 600-200 = 400km/hr = s2.
So, (Taking ratio of speed),
s1 : s2 = 600 : 400= 3 : 2.
So, time taken,
t1 : t2 = 2 : 3 (time and speed inversely proportional).
1 part time= 30 min.
So t1= 2*30 = 60 min = 1hr.
Maulik Gajjar said:
8 years ago
Change in in speed i.e speed reduced by 200 kmph then change in time is 30 mnts.
If speed reduce to zero i.e by 600kmph. Time taken will be 90 mnts.
As mentioned in the question, Flight took 30 months more.
To find the original time of flight, 90 -30 = 60 months, i.e 1 hour.
If speed reduce to zero i.e by 600kmph. Time taken will be 90 mnts.
As mentioned in the question, Flight took 30 months more.
To find the original time of flight, 90 -30 = 60 months, i.e 1 hour.
Varun said:
3 years ago
@Saravanakgopi.
It's wrong.
When you got 200 (x+30) =600. Then the next step would be 200x=600-6000. The result you get is negative.
So the final answer you get if you follow that method would be x= -27. So when you add it with increased time then -27+30 Which is 3.
It's wrong.
When you got 200 (x+30) =600. Then the next step would be 200x=600-6000. The result you get is negative.
So the final answer you get if you follow that method would be x= -27. So when you add it with increased time then -27+30 Which is 3.
(6)
Avesh said:
9 years ago
Let: Time = T, Speed = x
600/x = t ----> (1)
600/x - 200 = T + 1/2,
600/x - 200 = 3/2 T,
600 * 2/(x - 200) * 3 = T.
1200/3x - 600 = T---> (2)
BySolving..
1200/3x - 600 = 600/x.
3x - 600 = 2x.
x = 600.
Hence Speed is 600.
Since D/S = T.
D = 600.
S = 600.
T = 1.
600/x = t ----> (1)
600/x - 200 = T + 1/2,
600/x - 200 = 3/2 T,
600 * 2/(x - 200) * 3 = T.
1200/3x - 600 = T---> (2)
BySolving..
1200/3x - 600 = 600/x.
3x - 600 = 2x.
x = 600.
Hence Speed is 600.
Since D/S = T.
D = 600.
S = 600.
T = 1.
(1)
Saravanakgopi said:
1 decade ago
Another method: We know
Speed = Distance covered/ time taken
speed = 200km/hr
Distance=600km
time=x+30 (30 min. increase)
Apply the formule:
200 =600/x+30
200(x+30)=600
200x =5400
x = 27 min.
Now Time = x+30 so 27+30= 57 Min. Approx 1 Hr.
Speed = Distance covered/ time taken
speed = 200km/hr
Distance=600km
time=x+30 (30 min. increase)
Apply the formule:
200 =600/x+30
200(x+30)=600
200x =5400
x = 27 min.
Now Time = x+30 so 27+30= 57 Min. Approx 1 Hr.
Sanju said:
8 years ago
Hi, in question they mentioned.
d=600km , s=200kmph , t=30min.
Let duration of flight = x.
wkt SPEED=DISTANCE/TIME (s=d/t).
200 = 600/x - 600/x+(30/60).
200 = 600/x - 600*2/2x+1.
By solving this we get,
2x^2+2x-x = 0,
x=1.
d=600km , s=200kmph , t=30min.
Let duration of flight = x.
wkt SPEED=DISTANCE/TIME (s=d/t).
200 = 600/x - 600/x+(30/60).
200 = 600/x - 600*2/2x+1.
By solving this we get,
2x^2+2x-x = 0,
x=1.
Yogi said:
4 years ago
Simple,
Here is a trick, for such question, always break distance in its multiple,
For e,g.
600km = 300kmph x 2 hour.
Or
600km = 600kmph x1 hour
So we can see for 300kmph it takes 2 hours and for 600kmph it takes 1 hour.
And that's the answer.
Here is a trick, for such question, always break distance in its multiple,
For e,g.
600km = 300kmph x 2 hour.
Or
600km = 600kmph x1 hour
So we can see for 300kmph it takes 2 hours and for 600kmph it takes 1 hour.
And that's the answer.
(10)
Deepak Jain said:
1 decade ago
It is not mentioned in the problem that at what speed duration of flight to be find out because you are giving the answer for the speed before the bad weather.
According to me speed after bad weather should be taken and answer will be 1.5 hours.
According to me speed after bad weather should be taken and answer will be 1.5 hours.
NILESH DADARAO PAHURKAR said:
10 years ago
Flight 1st speed = 600 and due to bad weather average speed = 200 increased by = 30 minutes duration.
200 = 600/(x+30).
200(x+30) = 600.
200x + 6000 = 600.
200x = 600-6000 = 5400
x = 5400/200
x = 27.
x+30 = 27+30 = 57.
Answer: 57 min.
200 = 600/(x+30).
200(x+30) = 600.
200x + 6000 = 600.
200x = 600-6000 = 5400
x = 5400/200
x = 27.
x+30 = 27+30 = 57.
Answer: 57 min.
Ajit said:
1 decade ago
It's easy...the concept goes lik this...
consider eg.. for 50km speed-takes 1hr
for 50-y->1hr+t(in problem, speed is reduced and time is increased)
therfore,
600/x-600/x+(1/2)=200(on an avg (1hr+t) increased and on an avg 200km speed less)
consider eg.. for 50km speed-takes 1hr
for 50-y->1hr+t(in problem, speed is reduced and time is increased)
therfore,
600/x-600/x+(1/2)=200(on an avg (1hr+t) increased and on an avg 200km speed less)
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