Question

Only a single railway track is available for trains in Konkan area. A train travelling
with uniform speed of 50 km per hr. leaves station 'Ax' at 7.40 am to reach the
station By', which is situated at a distance of 100 km from 'Ax'. At 8.10 am a train
travelling with uniform speed of 40 km per hr. leaves station 'By' to reach the
station 'Ax'. The Traffic Controller noticed this situation at 8.40 am. Select the time
duration that the controller has mathematically, for making decision, for avoiding
collision between these two trains.
(1) 20 minutes
(2) 19 minutes
(3) 21 minutes
(4) 15 minutes​

Answer 1

Answer:

before  20 minutes

Step-by-step explanation:

A train travelling with uniform speed of 50 km per hr

leaves station 'Ax' at 7.40 am

=> Distance Covered till 8:40 am =  50 * 1 = 50 km

a train traveling with uniform speed of 40 km per hr.

leaves station 'By' At 8.10 am

=> Distance Covered till 8:40 am =  40 * 0.5 = 20 km

Hence total Distance Covered by train = 50 + 20 = 70 km

Distance between stations = 100 km

distance remained between Trains at 8:40 am = 100 - 70 = 30 km

Both trains speed together = 50 + 40 = 90 km/hr

Time left for collision = 30/90  = 1/3 hr

= 20 Mins

Decision has to be taken before 20 mins as after 20 min collision will happen