Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 4)
4.
Two trains running in opposite directions cross a man standing on the platform in 27 seconds and 17 seconds respectively and they cross each other in 23 seconds. The ratio of their speeds is:
Answer: Option
Explanation:
Let the speeds of the two trains be x m/sec and y m/sec respectively.
Then, length of the first train = 27x metres,
and length of the second train = 17y metres.
 |
27x + 17y | = 23 |
| x+ y |
27x + 17y = 23x + 23y
4x = 6y
| |
x | = | 3 | . |
| y | 2 |
Discussion:
237 comments Page 7 of 24.
Rohit said:
1 decade ago
Fast calculation = mod(23-17) : mod(23-27) = 6:4 = 3:2 .
Sujata said:
1 decade ago
I agreee with Rohit calculation.
Pallavi said:
1 decade ago
Can anyone tell me the formulas for relative speed ?
Jasminder said:
1 decade ago
27x+17y total distance.
X+y=total speed.
Total distance/total speed=total time.
Total time= 23 given.
Solve it.
X+y=total speed.
Total distance/total speed=total time.
Total time= 23 given.
Solve it.
Maha said:
1 decade ago
Distance=speed*time.
1st train time =27sec. 2nd train time =17sec.
two trains can cross the each other in opposite direction is 23 sec.
so total time=(total distance)/totalspeed;
total distance,
1st&2nd train have speed x,y;
total distance=27x+17y; total speed=x+y;
23=(27x+17y)/x+y;
23x+23y=27x+17y;
6y=4x;
6/4=x/y;
3/2=x/y;
3:2
1st train time =27sec. 2nd train time =17sec.
two trains can cross the each other in opposite direction is 23 sec.
so total time=(total distance)/totalspeed;
total distance,
1st&2nd train have speed x,y;
total distance=27x+17y; total speed=x+y;
23=(27x+17y)/x+y;
23x+23y=27x+17y;
6y=4x;
6/4=x/y;
3/2=x/y;
3:2
NICK said:
1 decade ago
Can any one tell me how to calculate mod(23-17) : mod(23-27)
I forgot how to calculate mod and if we are calculating same mod(23-17) : mod(23-27) then how it comes to 6:4????
I forgot how to calculate mod and if we are calculating same mod(23-17) : mod(23-27) then how it comes to 6:4????
Avinash said:
1 decade ago
First you have to know that mod(positive or negative value) = positive value
So mod(23-17)=6
mod(23-27)=mod(-4)=4
Hope you understood.
So mod(23-17)=6
mod(23-27)=mod(-4)=4
Hope you understood.
Rabish pandey said:
1 decade ago
Really it is helpful to get qualify related aptitude exam I thank from my side to indiabix. Com and easy to understand solution also.
Pardhu said:
1 decade ago
Avinash could you please explain clearly.
Ajit said:
1 decade ago
Dear rohit,
Your calculation right but this furmula use in every cases or limited case?
Your calculation right but this furmula use in every cases or limited case?
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