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 5 of 21.
Manik jaat said:
1 decade ago
Saravanakgopi can you please tell me that how you get 5400 instead of 600 ?
(1)
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
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....
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?
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?
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