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 9 of 21.
Sunita said:
1 decade ago
Hey Saravanakgopi. How did you get 5400? please explain.
Amit said:
1 decade ago
We know that 1/x inc in one quantity leds to 1/(x+1) dec in other quantity
1/(x+1)= 1/2
=> x=1
1/(x+1)= 1/2
=> x=1
Nivas said:
1 decade ago
@saravanakgopi.
What he said is wrong. Because he didn't convert hr into min. So that his method is wrong.
What he said is wrong. Because he didn't convert hr into min. So that his method is wrong.
Mukesh Singh said:
1 decade ago
Sorry Dear...
But I found sentence mistake is this Qs.
If in Qs it is asked that speed is reduced to 200km/hr then given solution is right.
But in qs it asked that speed is reduced by, so soln should be
600/(t+1/2) = 200
t = 5/2 hr
But I found sentence mistake is this Qs.
If in Qs it is asked that speed is reduced to 200km/hr then given solution is right.
But in qs it asked that speed is reduced by, so soln should be
600/(t+1/2) = 200
t = 5/2 hr
Anshu said:
1 decade ago
Let the time be x
600 / x = speed
1/2 hr = 30 mins
therefore,
600/x - 600 /x-1/2 = 200 [since speed = distance time^-1]
600/x - 1200/2x - 1 = 200
600(2x-1) - 1200(x)/ x(2x-1) = 200
2x^2 - x(200)= 600(2x-1) - 1200(x)
2x^2 - x = 3(2x -1 )- 6(x)
2x^2 - x = 6x - 3 - 6x
2x^2 - x = 3
2x^2 - x -3 = 0
(2x-3)(x-1) = 0
x = 1
or
x = 1.5
Since 1 hour is an alternative therefore the correct answer is 1 hour.
600 / x = speed
1/2 hr = 30 mins
therefore,
600/x - 600 /x-1/2 = 200 [since speed = distance time^-1]
600/x - 1200/2x - 1 = 200
600(2x-1) - 1200(x)/ x(2x-1) = 200
2x^2 - x(200)= 600(2x-1) - 1200(x)
2x^2 - x = 3(2x -1 )- 6(x)
2x^2 - x = 6x - 3 - 6x
2x^2 - x = 3
2x^2 - x -3 = 0
(2x-3)(x-1) = 0
x = 1
or
x = 1.5
Since 1 hour is an alternative therefore the correct answer is 1 hour.
Teju said:
1 decade ago
Hi Pavan......
you are mistaken it is not 3min. it is 30min.
so 30 min. is taken as 1/2 hr.
you are mistaken it is not 3min. it is 30min.
so 30 min. is taken as 1/2 hr.
Hari said:
1 decade ago
It's so simple like.
T= D/S => 600/300=30.
As it is given + 30 mins then 30+30 is 60=1 hour.
T= D/S => 600/300=30.
As it is given + 30 mins then 30+30 is 60=1 hour.
Amala said:
1 decade ago
@Mr. saravanagopi,
we already calculate the time as x+30 in [200(x+30)=600] right. then why did you again calculating the result as 27+30.
I don't understand...
we already calculate the time as x+30 in [200(x+30)=600] right. then why did you again calculating the result as 27+30.
I don't understand...
Rahul said:
1 decade ago
very very easy question
distance 600 km.
suppose aircraft speed is 600km/hr
time =600/600=1hr
ans=1hr
check method=speed decreasing 200km/h
speed is 400km/h distance 600
600/400=1.5=======30 mint late original duration is 1 hr..ans
distance 600 km.
suppose aircraft speed is 600km/hr
time =600/600=1hr
ans=1hr
check method=speed decreasing 200km/h
speed is 400km/h distance 600
600/400=1.5=======30 mint late original duration is 1 hr..ans
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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