A train 280 m long, running with a speed of 63 km/hr will pass a tree in

A.   15 sec.   
B.   16 sec.
C.   18 sec.
D.   20 sec.
Answer: B

Explanation:

Speed    = (63 x 5/18) m/sec
              = 35/2 msec
Time taken = (280 x 2 /35)m/sec
                  = 16 sec.