Aptitude - Problems on Trains - Discussion

One doubt.

According to this answer train taking 27 sec to cross the man having more speed than train taking 17 sec. As per my knowledge train taking more time having less speed anyone can explain this ?

---23------>----4-----|27
23<--6sec---|<---17sec----- Man

Train which takes 27 sec to cross a man takes 4 more seconds to cross man(27-23)
Train which takes 17 sec to cross a man takes 6 more seconds to cross train(23-17)
Let distance between crossover of train and man standing to be X
Speed ratio=x/4:x/6.
i,e 3:2.

Relative time 1st train= 27-23=4,
second train= 23-17=6,
1st:2nd= 6:4=3:2,
Ans:3:2.

(x+y) I am not understanding that where this comes here this question, please give answer.

Make it simple.

27-17 =6 :27-23 =4
6:4 or 3:2.

@Sudhan.

Isn't 27-17 = 10? How do you say it's 6?

Two trains are moving in opposite direction with the speed of 36 k.m. /h and 54 k.m. /h cross each other in 12 seconds. The length of the 2nd train is half of the 1st train. The 1st train crosses a platform in 1. 30 minutes. Then what is the length of the platform? Please solve this.

860m, It consists of two cases.

Very clear explanations. Thanks.

Speed=(distance/time).

It rewritten as (distance/speed)=time.
Same case:
(relative distance/relative speed)=time
We understand the only thing how to calculate relative speed and relative distance,
Consider car A travel at x km/hr and car B travels at y km/hr
Both A and B travel in same direction means
Their relative speed=subtraction of two speed (x+y)km/hr.
Relative distance= (speed1*time1)-(s2+t2).
=27x-17y.

Here 27 and 17 are time1 and time2.
X and y are speed1 and speed2.

Case2:
CarA and carB travels opposite direction.
Relative speed= x+y(addition of speeds)
Relative distance=(speed1*time1)+(s2*t2)
So we get. = 27x+17y.
Finally (relative distance/relative speed)=time,
Therefore (27x+17y)/(x+y)=23,

Maybe my solutions help for you