A) 70 km/h
B) 200 km/h
C) 250 km/h
D) 350 km/h
Correct Answer: A
Solution :
[a] Let the speed of first train be 7x km/h. Then, the speed of the second train is 8x km/h. But, speed of the second train \[=\frac{400}{5}\,km/h=80\,km/h\] \[\therefore \] \[8x=80\]\[\Rightarrow \]\[x=10\] Hence, the speed of first train is \[(7\times 10)\,km/h=70\,km/h.\] |
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