Correct Answer - Option 5 : 40 km
Given:
Distance between pt. A and pt. B = 90 km
Time taken by faster train to cover the distance = 3 hrs
Ratio of speed = 4 : 5
Concept:
In these types of questions, we find the speed of both the trains and then find the distance cover in 3 hrs and then we use the relative speed concept.
Formula:
Relative speed = S1 + S2 (when direction is opposite)
Distance = speed × time
Calculation:
Let the speed of the faster and slower trains be 5x and 4x respectively
⇒ 90 = 5x × 3
⇒ x = 6
Speed of faster train = 5x = 5 × 6 = 30 km/hr
Speed of slower train = 4x = 4 × 6 = 24 km/hr
Time of meeting = 90/(30 + 24) = 1.67 hour = 100 min
∴ Distance from point B = 24 × 100/60 = 40 km