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 3 of 9.
Abi said:
9 years ago
200/x + 400/y = 25/3.
200 (1/x + 2/y) = 25/3.
1/x + 2/y = 25/3 * 200 (multiply 3 * 200).
1/x + 2/y = 25/600.
1/x + 2/y = 1/24.
By solving this, we get 3 : 4.
200 (1/x + 2/y) = 25/3.
1/x + 2/y = 25/3 * 200 (multiply 3 * 200).
1/x + 2/y = 25/600.
1/x + 2/y = 1/24.
By solving this, we get 3 : 4.
(1)
Karan K N said:
4 years ago
@Karan.
It's Given in the question;
Distance by train=200.
Remaining distance by car, So 600-200 = 400 is the distance covered by a car.
It's Given in the question;
Distance by train=200.
Remaining distance by car, So 600-200 = 400 is the distance covered by a car.
(3)
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.
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)
Sukanya said:
1 decade ago
Convert 20 minutes into hrs, 20/60 = 1/3 hrs.
Since it s 20 minutes more than the 8 hrs,
Total time = (1/3)+8 = 25/3 hrs.
Since it s 20 minutes more than the 8 hrs,
Total time = (1/3)+8 = 25/3 hrs.
Sunil Kumar said:
10 years ago
@Siri.
Since we have to find the speeds of train and car, we need to solve for x and y. So we need addition here.
Since we have to find the speeds of train and car, we need to solve for x and y. So we need addition here.
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.
120/x + 480/y = 8,
1/x + 4/y = 8/120,
= 1/15.
D.Rajkumar said:
7 years ago
The second one takes 20 minute more then time is 8:20 but 25/3 is 8.3.
So, 33/4 is 8.2 is correct
So, 33/4 is 8.2 is correct
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.
Siri said:
10 years ago
I can't understand to 1/x +4/y =1/15 and 1/x +2/y =1st/24 why they take addition in this step?
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