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 7 of 9.
Sandy said:
1 decade ago
Please can any one tell me how did you get the 8 in first step?
Deepu said:
1 decade ago
By doing eqn(1) - eqn(2) we can get:
(4/y)-(2/y) = (1/15)-(1/24)
(4y-2y)/y2=(8-5)/120
2y/y2=3/120
2/y=1/40
y=80
By placing y value in eqn(1) we get x = 60.
(4/y)-(2/y) = (1/15)-(1/24)
(4y-2y)/y2=(8-5)/120
2y/y2=3/120
2/y=1/40
y=80
By placing y value in eqn(1) we get x = 60.
Bharatesh said:
1 decade ago
Please tell me how did you get the X value?
Shwetha said:
1 decade ago
Hi das 120 (1/x+4/y) = 8 then 1/x+4/y=8/20 that is equal to 1/x+4/y=1/15.
Das said:
2 decades ago
Hi could you tel me how this 1/15 came in Step 1 ?
Anu said:
2 decades ago
Hey as it takes 20mins more for car to travel 200km... then time becomes 8hrs20mins.... so by converting dis time totally into hrs... 8*(20/60)...dis fraction brings u 25/3.
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.
Subash said:
9 years ago
I can't understand. How to get eqn (1) and eqn (2)? Anyone can explain full steps?
Sathish said:
9 years ago
How 120/x + 480/y = 8?
Deep said:
9 years ago
Can anyone explain it properly how we got 1/24?
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