# Easy Time, Speed & Distance Solved QuestionAptitude Discussion

 Q. A train covered a certain distance at a uniform speed. If the train had been 6 km/hr faster, it would have taken 4 hour less than the scheduled time. And, if the train were slower by 6 km/hr, the train would have taken 6 hr more than the scheduled time. The length of the journey is:
 ✖ A. 700 km ✖ B. 740 km ✔ C. 720 km ✖ D. 760 km

Solution:
Option(C) is correct

Let the length of the journey be d km and the speed of train be $S$ km/hr.

Then,

$\dfrac{d}{S+6}=t-4$-----(i)

$\dfrac{d}{S-6}=t+6$------(ii)

Subtracting the 1 equation from another we get:

$\dfrac{d}{S-6}-\dfrac{d}{S+6}=10$------(iii)

Now $t=\dfrac{d}{s}$

Substitute in equation (i) and solve for $d$ and $S$

We get $S = 30$ and  $d$ = 720 km

## (2) Comment(s)

Madhu
()

By solving equation (3) I got d=5/2 anybody help me how d= 720km

GAURAV AGRAWAL
()

simplifying equation 1

d=ts-4s+6t-24

put ts=d

we get eq

-4s+6t=24

-2s+3t=12......eq(3)

similiarly solve for equation 2

we get

s-t=6.........eq(4)

from 3 and 4 we get t=24 and s=30