13.A 300 metre long train crosses a platform in 39 seconds while it crosses a signal pole in 18 seconds. What is the length of the platform ?
A. 320 m B. 350 m
C. 650 m D. None of these
Answer:B
Speed = (300 / 18) m/sec
= (50 / 3) m/sec.
Length of the platform be x metres.
Then = x + 300 /39
= 50 / 3 m/sec
= 3 (x + 300) =1950 .
= 350 m
