7.A train covers a distance of 12 km in 10 minutes. If it takes 6 seconds to pass a telegraph post, then the length of the train is
A. 90 m B. 100 m
C. 120 m D. 140 m
Answer:C
Speed = (12 / 10 x 60)km/hr
= (72 x 5/18) m/sec
= 20 m/sec.
Length of the train = (speed x time )
= (20 x 6)m
= 120 m.
