Question

ATrain whose length is120m,crosses the bridge in12sec.at a speed of60km/hr.What is the length of the bridge?

Answer 1

Answer:

If train cross its length in 12 seconds and 170 m bridge in (36 - 12 = 24) seconds.

Speed of train = [170/24] × [18/5] = 25.5 km/hr

Detailed method:

Let the length of the train be x m.

As we know,

Speed = Distance/time

Speed = x/12 ---(1)

Speed = (x + 170)/36 ---(2)

Frome equation (1) and equation (2)

x/12 = (x + 170)/36

⇒ 3x = x + 170

⇒ 2x = 170

⇒ x = 170/2

⇒ x = 85 m

From equation (1)

Speed = 85/12 × (18/5) km/hr

∴ Speed = 25.5 km/hr