Q6 of 7 Page 67

A train covers a certain distance at a uniform speed. If the train had been 10 km/hr faster it would have taken 2 hours less than the scheduled time. If the train was slower by 10 km/hr it would have taken 3 hours more than the scheduled time. Write the two equations.

Let the speed of train be s km/hr as for “d” km it would take “t” hr.

We know that, Distance = Speed × Time


Therefore, d = s × t


According to question, for the same distance d,if speed increases by 10km/hr


time will decrease by 2hr,i. e,


d = (s + 10)(t – 2)


d = st – 2s + 10t – 20


2s – 10t = – 20


s – 5t = – 10 ……(i)


Also, for the same distance d, if speed decreases by 10/hr time will increase by 3hr,i. e,


d = (s – 10)(t + 3)


d = st + 3s – 10t – 30


3s – 10t = 30 …… (ii)


(i)&(ii) are the required equations.


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