Correct Answer - Option 1 : 45 km/h
Calculation:
Let speed of the train be x km/hr and length of the train be d m.
As we know
Distance = Speed × Time
⇒ Distance = x × 5/18 × 20 ---(1)
Again,
Distance = 18 × (x + 5) × 5/18 ---(2)
From equation (1) and equation (2)
⇒ x × 5/18 × 20 = 18 × (x + 5) × 5/18
⇒ 20x = 18x + 90
⇒ 20x – 18x = 90
⇒ 2x = 90
⇒ x = 90/2
⇒ x = 45 km/hr