Question

A train leaves the station 1 hour before the scheduled time. The driver decreases its speed by 2 km/h. At the next station 60 km away, the train reached on time. Find the original speed of the train?​

Answer 1

original speed be s and time taken be t, then distance = 60km = st

s =60/t

now time taken, t1 = t+1

speed s1 = s-2

distance =60 = (s-2)(t+1)

= st-2t+s-2 = st

s -2t =2

60/t -2t =2

60-2t² =2t

2t²+2t-60 =0

2t²+12t-10t-60 =0

2t(t+12) -10(t+12) =0

(2t-10)(t+12)=0

t=10/2=5hrs

s = 60/5 = 12 kmph