Aptitude - Time and Distance - Discussion
Discussion Forum : Time and Distance - General Questions (Q.No. 8)
8.
The ratio between the speeds of two trains is 7 : 8. If the second train runs 400 km in 4 hours, then the speed of the first train is:
Answer: Option
Explanation:
Let the speed of two trains be 7x and 8x km/hr.
| Then, 8x = |  |
400 |  |
= 100 |
| 4 |
 x = |
|
100 | |
= 12.5 |
| 8 |
Speed of first train = (7 x 12.5) km/hr = 87.5 km/hr.
Discussion:
51 comments Page 1 of 6.
Asit said:
1 decade ago
Let the speed of 1st train is x km/hr
2nd train speed =distance/time
So 400/4=100km/hr
now given that their ratio= 7:8(i.e 1st/2nd)
so x/100 = 7/8
=>x=87.5km/hr
2nd train speed =distance/time
So 400/4=100km/hr
now given that their ratio= 7:8(i.e 1st/2nd)
so x/100 = 7/8
=>x=87.5km/hr
Prajweetha said:
1 decade ago
Second train runs at 400kms in 4 hours, so in 1 hour its speed is 400/4=100kms/hr.
Let speed of first train be "x".
Ratio is 7:8=x:100.
Then 8x=7*100.
X=700/8.
=87. 5km/hr.
Let speed of first train be "x".
Ratio is 7:8=x:100.
Then 8x=7*100.
X=700/8.
=87. 5km/hr.
Sandeep said:
1 decade ago
Its a ration sum..
then..
Second train runs at 400kms in 4 hours, so in 1 hour its speed is 400/4=100kms/hr.
Now according to ratio concept:-
7:8
means..
total is 15..
then 8/15*x=100
we get,187.5 total speed of both the tain.
now
for first train speed..
7/15*187.5= 87.5 km/hr
then..
Second train runs at 400kms in 4 hours, so in 1 hour its speed is 400/4=100kms/hr.
Now according to ratio concept:-
7:8
means..
total is 15..
then 8/15*x=100
we get,187.5 total speed of both the tain.
now
for first train speed..
7/15*187.5= 87.5 km/hr
Anshu said:
1 decade ago
Speed of the 2nd train =
Total distance it traveled / total time taken
= 400 / 4 = 100kmph
Therefore,
according to the ratio provided,
8x = 100 kmph
x = 12.5 kmph
therefore the the speed of the second train =
7x = 7 (12.5) = 87.5 kmph
I hpoe that is easy.
Total distance it traveled / total time taken
= 400 / 4 = 100kmph
Therefore,
according to the ratio provided,
8x = 100 kmph
x = 12.5 kmph
therefore the the speed of the second train =
7x = 7 (12.5) = 87.5 kmph
I hpoe that is easy.
Vellamuthu said:
1 decade ago
Ratio 7:8
Speed =400/4 km/hr
speed =x
x=400/4 km/hr
4x=400 km
Second train Ratio 8*50=400=4x
Ratio 7*50=4x
350=4x
x=350/4
x=350/4
x=87.5 km/hr
Speed =400/4 km/hr
speed =x
x=400/4 km/hr
4x=400 km
Second train Ratio 8*50=400=4x
Ratio 7*50=4x
350=4x
x=350/4
x=350/4
x=87.5 km/hr
Mihir jack said:
1 decade ago
Let this try :
Assume 7:8 = 7/8 = 0.875
Now 0.875 % less speed than 2nd train ,
Now simple 0.875 *100 = 87.5 answer
Assume 7:8 = 7/8 = 0.875
Now 0.875 % less speed than 2nd train ,
Now simple 0.875 *100 = 87.5 answer
Amala said:
1 decade ago
7:8
100kmph - 8
? - 7 ( so cross multiplication)
(7*100)/8=87.5
100kmph - 8
? - 7 ( so cross multiplication)
(7*100)/8=87.5
Rahul said:
1 decade ago
Train 2 speed is 100km/hr
100/8=12.5
12.5*7=87.5 train 1 speed =answer
100/8=12.5
12.5*7=87.5 train 1 speed =answer
Avnish poddar said:
1 decade ago
Let speed of first train is "x"
And speed of second train is ""y"
Therefore given ratio are (x/y) = (7/8).
x = (7/8)*y = 87.5 kmph : Answer.
Where y =(400/4) = 100.
And speed of second train is ""y"
Therefore given ratio are (x/y) = (7/8).
x = (7/8)*y = 87.5 kmph : Answer.
Where y =(400/4) = 100.
Manish Singh said:
1 decade ago
7/8 = X/(400/4).
Now find the X,
It will come 87.5 KM/hr.
Here X is the speed of first train.
Now find the X,
It will come 87.5 KM/hr.
Here X is the speed of first train.
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