Correct Answer - Option 2 : 70 kmph
Given:
The ratio of the speeds of two trains is 7 : 8
Distance = 400 km
Time is taken by the second train to cover distance = 5 hr
Formula used:
Speed = Distance/Time
Calculation:
Let the speed of the train be ‘x’
Speed of train 1 = 7x
Speed of train 2 = 8x
The second train covers 400 km distance in 5 hr
⇒ 8x = 400/5
⇒ x = 10
Speed of train 1
⇒ 7x = 7 × 10
⇒ 70 km/h
∴ The speed of the first train is 70 km/h.
