A train 800 metres long is travelling at 78 kilometres per hour. If it travels through a tunnel in one minute, the tunnel's length (in metres) is
A. 130
B. 360
C. 500
D. 540
Answer:C
A train 800 metres long is travelling at 78 kilometres per hour. If it travels through a tunnel in one minute, the tunnel's length (in metres) is
A. 130 B. 360 C. 500 D. 540
Explanation: Speed = ( 78 x 5/18 m/sec ) m/sec = ( 65/3 ) m/sec.1 minute equals 60 seconds. Let's say the tunnel is x metres long.As a result, ( 800 + x/60 ) = 65/3, 3 x (800 + x)=3900 => x equals 500.