Aptitude - Time and Distance - Discussion
Discussion Forum : Time and Distance - General Questions (Q.No. 4)
4.
A train can travel 50% faster than a car. Both start from point A at the same time and reach point B 75 kms away from A at the same time. On the way, however, the train lost about 12.5 minutes while stopping at the stations. The speed of the car is:
Answer: Option
Explanation:
Let speed of the car be x kmph.
| Then, speed of the train = | 150 | x | = |  |
3 | x |  kmph. |
| 100 | 2 |
 |
75 | - | 75 | = | 125 |
| x | (3/2)x | 10 x 60 |
 |
75 | - | 50 | = | 5 |
| x | x | 24 |
| x = |
|
25 x24 | |
= 120 kmph. |
| 5 |
Discussion:
345 comments Page 15 of 35.
Rajesh said:
1 decade ago
Assume the car speed as 120 km/hr.
If cars speed is 120 km/hr then it reaches 75 km in 37.5 min(explained below).
Since 120 km/hr is 120 km/60 min, which is 2 km/1 min.
Therefore for 75 km it takes 37.5 min.
Train speed is 50% higher so it will be 180km/hr.
180 km/hr is 180 km/60 min, which is 3km/min.
Therefore for 75 km it takes 25 min.
It lost 12.5 min in stopping so total time taken by train is (25+12.5) = 37.5 min.
Therefore our assumption is correct. Answer is 120 km/hr.
If cars speed is 120 km/hr then it reaches 75 km in 37.5 min(explained below).
Since 120 km/hr is 120 km/60 min, which is 2 km/1 min.
Therefore for 75 km it takes 37.5 min.
Train speed is 50% higher so it will be 180km/hr.
180 km/hr is 180 km/60 min, which is 3km/min.
Therefore for 75 km it takes 25 min.
It lost 12.5 min in stopping so total time taken by train is (25+12.5) = 37.5 min.
Therefore our assumption is correct. Answer is 120 km/hr.
Somya said:
1 decade ago
@Neo, your method is good. I just want to know how you got that 32.5? please elaborate?
Sandeep said:
1 decade ago
Let as take car speed as =100 than train speed is 50% faster than car so 100+50=150.
K. srinivasan said:
1 decade ago
Let the speed of the car be 10km/h and so as the speed of the train is 50% more ie 50% of 10 is 5 and so the speed of the train can be assumed to be 15km/h. Based on this assumption also this problem can be solved.
Sandy said:
1 decade ago
Please any one can explain the equation [75/x]-[75/1.5x] = [12.5/60].
Gauravnagayach said:
1 decade ago
please explain:
(x+(50/100)*x)= 3x/2
Where 3x/2 & how 150/100?
(x+(50/100)*x)= 3x/2
Where 3x/2 & how 150/100?
Neo said:
1 decade ago
Here 150/100 how it come means.
Actually they said train 50%more than speed of car.
So train actually speed was 100% means 100/100 and he said 50 more so 150/100 that's it.
Actually they said train 50%more than speed of car.
So train actually speed was 100% means 100/100 and he said 50 more so 150/100 that's it.
Shivu said:
1 decade ago
Can you please tell me how that 125/(10x60) came?
Sri said:
1 decade ago
How 125/ (10*60) came?. Anyone please explain this point.
Vidhya said:
1 decade ago
We need to convert 12.5 min to hours because the options given are in kmph (kilometre per hour).
To convert 12.5 min to hours you divide it by 60.
To make calculation easier 12.5 is converted into 125 by multiplying it by 10. If you multiply numerator with a number, then you also have to multiply denominator by that number.
Hence in this case it will be 12.5*10/60*10 = 125/600 which is actually the same as 12.5/60.
125/600 = 5/24.
12.5/60 = 5/24.
To convert 12.5 min to hours you divide it by 60.
To make calculation easier 12.5 is converted into 125 by multiplying it by 10. If you multiply numerator with a number, then you also have to multiply denominator by that number.
Hence in this case it will be 12.5*10/60*10 = 125/600 which is actually the same as 12.5/60.
125/600 = 5/24.
12.5/60 = 5/24.
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