Question

A train running at the speed of 80 km/h crosses a 350 m long tunnel in 36 seconds. What is the length of the train (in meters)?

• A. 350
• B. 380
• C. 420
• D. 450

Answer 1

The Correct Option is D

Let the length of the train be \(L\) meters. 

The train is running at 80 km/h, which is \(80 \times \frac{1000}{3600} = \frac{800}{36} = \frac{200}{9}\) m/s.

The train crosses a 350 m long tunnel in 36 seconds. 

The total distance the train covers is the length of the train plus the length of the tunnel: \(L + 350\) meters.

Distance = Speed × Time, so \(L + 350 = \frac{200}{9} \times 36 = 200 \times 4 = 800\).

\(L = 800 - 350 = 450\) meters.

Answer 2

The speed of the train is 80 km/h, which is converted to meters per second as $80 \times \frac{1000}{3600} = 22.22$ m/s. 

The total distance covered by the train in 36 seconds is $22.22 \times 36 = 800$ meters. 

The length of the train is $800 - 350 = 450$ meters.