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 17 of 21.
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
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...
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.
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.
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.
Manik jaat said:
1 decade ago
Saravanakgopi can you please tell me that how you get 5400 instead of 600 ?
(1)
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
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.
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
Sunita said:
1 decade ago
Hey Saravanakgopi. How did you get 5400? please explain.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers