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 9 of 9.
Manisha said:
1 decade ago
How this 8 value came in equation any one can you please explain?
Rajani said:
1 decade ago
I have tried putting y as 5 in both the equation but it is not giving x as 60. Please explain.
Rakesh said:
1 decade ago
Do we any alternative method for this because this method is time consuming.
Satish said:
1 decade ago
(200/x)+(400/y) = 8+(20/60).
=> 200(1/x+2/y) = 25/3.
=> 1/x+2/y = 25/(3*200).
By cancellation we get,
1/x+2/y = 1/24.
=> 200(1/x+2/y) = 25/3.
=> 1/x+2/y = 25/(3*200).
By cancellation we get,
1/x+2/y = 1/24.
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