A train crosses a pole in 5 seconds and crosses the tunnel in 20 seconds. If the speed of the train 90 m/s, then find the length of the tunnel.

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  1. 1350 m
  2. 900 m
  3. 1200 m
  4. 800 m

Answer (Detailed Solution Below)

Option 1 : 1350 m
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Detailed Solution

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Given:

Time to cross the pole = 5 sec

Time to crosses the tunnel = 20 sec

Formula used:

Speed = Distance/Time

Calculation:

Let the length of the tunnel be x m and the length of the train be y m

Time = Distance/Speed

⇒ 5 = (y/90)

⇒ y = 450 m

Time to crosses the tunnel = Distance/Speed

⇒ 20 = (y + x)/90

⇒ 20 × 90 = (450 + x)

⇒ x = 1800 - 450 = 1350

∴ The length of the tunnel is 1350 m.

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