Question

find in how much time it will cross both bridge and platform.​

Answer 1

Answer:

a) 12 seconds

Hope this helps you.

Step-by-step explanation:

The 110 m long train passes a man in 3 sec.  So it takes 3 sec to travel 110 m.

The platform is 165 m.  The bridge is 135 m.  They are 30 m apart.  So the distance past both platform and bridge is (165 + 135 + 30) m = 330 m.

So from front of train arriving at platform to front of train leaving the bridge, the train travels 330 m.  To completely clear the bridge, the train must travel another 110 m so that the back of the train is also across.

In total, train must travel 440 m to completely pass platform and bridge.

It takes 3 sec to travel 110 m, so...

it takes 12 sec to travel 440m.