Question

A train, which moves with uniform speed for a

certain distance takes 6 hours less if its speed is

increased by 6km per hour, it would have taken 6 hours

more, had its speed been decreased by 4km per hour.

Find the distance of the journey and the speed of the

train.​
​

Answer 1

From formula 

D=st

given

D=(s+6)(t-4)=st-4s+6t-24.......>1

D=(s-6)(t+6)=st+6s-6t-36)......>2

from 1&2 

-4s+6t=24

6s-6t=36 .....>3

on solving  

2s=60 ==> s=30 km/h

(3)==> 6(30)-6t=36

t= 24 h

.

. . D=30(24) = 720 km

Ans: D= 720 km

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