Model 3 Train Vs Bridge/Platform Practice Questions Answers Test with Solutions & More Shortcuts

Answer: (d)

Using Rule 10,

Speed of train = 72 kmph

= $({72 × 5}/18)$ m/sec.

= 20 m/sec.

Required time

= $\text"Length of train and bridge"/ \text"Speed of train"$

= ${(200 + 800)}/20$

= $1000/20$ = 50 seconds

Answer: (b)

Using Rule 1,

When a train crosses a bridge it covers the distance equal to length of Bridge & its own length

Let the length of the train be = x

Speed of the train

= ${x + 800}/100$ m/s

Since train passes the 800 m bridge in 100 seconds.

Again, train passes the 400 m bridge in 60 seconds.

${400 + x}/{{x + 800}/100} = 60$

${(400 + x) × 100}/{x + 800}$ = 60

40000 + 100x = 60x + 48000

100x - 60x = 48000 - 40000

40x = 8000 ⇒ x = $8000/40$ = 200m