A train travelling at the speed of 72 km/hr crosses

Solution

Speed of longer train = 72 × (5/18) = 20 m/s
Speed of shorter train = 54 × (5/18) = 15 m/s

Let length of longer and shorter trains be ‘L’ meters and (L – 40) metres, respectively.

According to question,

L + L – 40 = (20 + 15) × 6 = 210

2L – 40 = 210

L = 125 metres

So, L – 40 = 85 metres

Let length of platform is ‘P’ metres

So, P + 125 = 20 × 14 = 280

P = 280 – 125 = 155 meters

Desired time = (155 + 85)/15 = 240/15 = 16 seconds