A train does a journey without stopping in 12 hours. If it had travelled 30 km an hour faster, it would have done the journey in 6 hours 40 min. What is its slower speed?
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Answer:
37.5km/h
Step-by-step explanation:
Let slower speed be x km/h
speed= distance/time
x=distance/12
distance=12x-----1
when it travels 30km/h faster,
its speed will be (x+30) km/h
speed=distance/time
x+30=distance/(6hrs 40 mins)
x+30=distance/(6hrs+2/3hrs)
x+30=distance/(20/3)hrs
distance=20(x+30)/3--------2
since the two conditions are about the same journey,
12x=(20x+600)/3
36x=20x+600
16x=600
x=37.5km/h
thus slower speed=37.5km/h.
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