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Aptitude - Time and Distance - Discussion

Discussion Forum : Time and Distance - General Questions (Q.No. 13)
Time and Distance
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:
2 : 3
3 : 2
3 : 4
4 : 3
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 4 of 9.
Siddhant ojha said:   8 years ago
The solution given is not right because of 8+2/3=26/3 not 25/3.
Chandu Balaji said:   8 years ago
Can we use alligation method here. Please clarify my doubt?
Dhirendra mehta said:   8 years ago
How comes 3?
ID.PRASAD said:   8 years ago
@Liton Das.

200/x +400/y = 25/3,
Now, 200 common.
200 (1/x+2/y) = 25/3.

(1/x+2/y) = (25/3) * (1/200),

After the cancellation,
We get,
(1/x+2/y) = 1/24,

Got it.
Liton das said:   8 years ago
25/3 how did it convert to 1/24?

Please explain.
Namita said:   9 years ago
How, from where that 1/15 came?
(1)
Pradeep said:   9 years ago
In first equation divide both sides by 120 then we get 1/15.

120/x + 480/y = 8,
1/x + 4/y = 8/120,
= 1/15.
Gopikrishna said:   9 years ago
How you get 1/15?

Please answer me.
Subash said:   9 years ago
I can't understand. How to get eqn (1) and eqn (2)? Anyone can explain full steps?
Soumitra said:   9 years ago
It takes more 20 min. It means 8hr + 20 min. Now convert into hr then it comes 20/60= 1/3. So time is 8hr+1/3hr= 25/3 hr.
(2)
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