Aptitude - Time and Distance - Discussion
Discussion Forum : Time and Distance - General Questions (Q.No. 13)
13.
It takes eight hours for a 600 km journey, if 120 km is done by train and the rest by car. It takes 20 minutes more, if 200 km is done by train and the rest by car. The ratio of the speed of the train to that of the cars is:
Answer: Option
Explanation:
Let the speed of the train be x km/hr and that of the car be y km/hr.
| Then, | 120 | + | 480 | = 8  |
1 | + | 4 | = | 1 | ....(i) |
| x | y | x | y | 15 |
| And, | 200 | + | 400 | = | 25 | |
1 | + | 2 | = | 1 | ....(ii) |
| x | y | 3 | x | y | 24 |
Solving (i) and (ii), we get: x = 60 and y = 80.
Ratio of speeds = 60 : 80 = 3 : 4.
Discussion:
84 comments Page 5 of 9.
Anjali said:
7 years ago
Thanks @Rahul Singh.
P Chandini said:
7 years ago
If the ratio is known 3:4. How can we find the speed?
Yoonie said:
7 years ago
@D.Rajkumar.
Actually when we say 8.2, the 0.2 there is out of 1 unit or 2 out of 10 or 2 out of 100. There are however 60 minutes in 1 hour which means the same concept cannot be applied since we are calculating out of 60 and not 100. 25/3 is absolutely correct.
Actually when we say 8.2, the 0.2 there is out of 1 unit or 2 out of 10 or 2 out of 100. There are however 60 minutes in 1 hour which means the same concept cannot be applied since we are calculating out of 60 and not 100. 25/3 is absolutely correct.
Prashant said:
7 years ago
Thanks @Rahul Singh.
Deepu said:
5 years ago
Please, show how to solve equation 1 and 2 step by step? Anyone explain, please.
Juwel said:
6 years ago
It takes 4 hours for 300 km whereof 60 km is covered by train and the rest by car. It takes 20 min more if 100 km is covered by train and rest by car then what is the ration. Please explain.
Sainath said:
6 years ago
How did we got 25/3?
Kavitha said:
1 decade ago
Hi manasa,
let the speed of the train be x kmph
let the speed of the car be y kmph
it is given that 120km is done by train,so D=120
by the formula D=S*T
T=120/X
and also given the rest is done by the car,
so D=600-120=480 km
T=480/y
then,120/x+480/y=8(read the question given problem clearly,in pbm it is given that to complete 600km journey,it will take 8hrs).
==>1/x+4/y=1/15...............eq1
similarly in case 2:
time for
train=200/x
car=400/y
and also given in pbm 20 min more so,
200/x+400/y=25/3(8hrs+20min=25/3)
==>1/x+2/y=1/24...............eq2
for solving these two equations as mathi said
then u will get 3:4
Hope u understand.
Bye
let the speed of the train be x kmph
let the speed of the car be y kmph
it is given that 120km is done by train,so D=120
by the formula D=S*T
T=120/X
and also given the rest is done by the car,
so D=600-120=480 km
T=480/y
then,120/x+480/y=8(read the question given problem clearly,in pbm it is given that to complete 600km journey,it will take 8hrs).
==>1/x+4/y=1/15...............eq1
similarly in case 2:
time for
train=200/x
car=400/y
and also given in pbm 20 min more so,
200/x+400/y=25/3(8hrs+20min=25/3)
==>1/x+2/y=1/24...............eq2
for solving these two equations as mathi said
then u will get 3:4
Hope u understand.
Bye
Srijan said:
1 decade ago
How it comes 25/3 please explain?
Moumita roy said:
1 decade ago
I can't understand to 1/x +4/y =1/15 and 1/x +2/y =1st/24.
Then how will do x=60 y=80?
Then how will do x=60 y=80?
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