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.
Har said:
10 months ago
400/4 = 100 km/hr.
after this;
100/8 = 12.5 parts of the second train.
100 - 12.5 = 87.5 km/hr for the first train.
after this;
100/8 = 12.5 parts of the second train.
100 - 12.5 = 87.5 km/hr for the first train.
(4)
VIJETH bk said:
1 year ago
The Speed of a second train is:
400/4 = 100km/hr.
The Ratio that is given if the speed is 7:8;
=> 7 : 8 = x : 100.
X is the speed of the first train and 100 is the speed of the second train.
7/8 = x/100.
X = 7×100/8.
X = 87.5km/hr.
400/4 = 100km/hr.
The Ratio that is given if the speed is 7:8;
=> 7 : 8 = x : 100.
X is the speed of the first train and 100 is the speed of the second train.
7/8 = x/100.
X = 7×100/8.
X = 87.5km/hr.
(18)
Arjun said:
1 year ago
The right answer is 87.5 km/hr.
(2)
Bharathviswa said:
2 years ago
Let the second train covers 400 in 4 hrs.
So, per hour it covers 100 km.
so, we have a ratio of 7:8.
if we consider 100 km in units each 10 km will be 1 unit.
But we have only 8 units so here 1 unit is equal to 12.5 km.
12.5 x 8 = 100.0.
then, 12.5 x 7 = 87.5 kms.
So, per hour it covers 100 km.
so, we have a ratio of 7:8.
if we consider 100 km in units each 10 km will be 1 unit.
But we have only 8 units so here 1 unit is equal to 12.5 km.
12.5 x 8 = 100.0.
then, 12.5 x 7 = 87.5 kms.
(8)
AKHILA MALKANI said:
2 years ago
Simple, just consider their ratios and equate :
S1:S2 = 7:8.
Let's consider x is the speed of train1;
x/8 = 7/88x= 700.
x= 700/8 = 87.5.
S1:S2 = 7:8.
Let's consider x is the speed of train1;
x/8 = 7/88x= 700.
x= 700/8 = 87.5.
(2)
Meghan Desai said:
2 years ago
@all.
Here is an easy explanation;
So,
speed of second car = D/T = 400/4 =100kmph.
Now we have;
7:8::x:100 (let the speed of the first car is x)
i.e
7/8 = x/100
Therefore,
8x=700;
x = 700/8 &
x = 87.5kmph.
Thank you!
Here is an easy explanation;
So,
speed of second car = D/T = 400/4 =100kmph.
Now we have;
7:8::x:100 (let the speed of the first car is x)
i.e
7/8 = x/100
Therefore,
8x=700;
x = 700/8 &
x = 87.5kmph.
Thank you!
(46)
Senthilkumaran S said:
2 years ago
Firstly, find the speed of the second Train = 400/4 = 100kmph.
7/8 = x/100,
x = 700/8,
x = 87.5.
7/8 = x/100,
x = 700/8,
x = 87.5.
(20)
Sivaprakash said:
3 years ago
Just consider 7:8.
X is speed of first flight.
Speed of the second S=D/S=400/4=100kmph;
8=100 and 7=?.
8/100=7/x=? Cross multiplicate.
100*7/8=87.5.
X is speed of first flight.
Speed of the second S=D/S=400/4=100kmph;
8=100 and 7=?.
8/100=7/x=? Cross multiplicate.
100*7/8=87.5.
(8)
Choden said:
4 years ago
@All.
The ratio is7:8::x:400.
Simply multiply extremes(400*7) and divide by 8x(mean).
400*7=2800÷8,
=350.
Now 350÷4=87.5.
The ratio is7:8::x:400.
Simply multiply extremes(400*7) and divide by 8x(mean).
400*7=2800÷8,
=350.
Now 350÷4=87.5.
(3)
Yogi said:
4 years ago
7/8 = x/100,
7*100/8 = x,
87.5 = x.
7*100/8 = x,
87.5 = x.
(14)
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