A and B go around a circular track of length 200 m on a cycle at speeds of 36 kmph and 72 kmph. After how much time will they meet for the first time at the starting point?
Choose one:  A) 120 sec  B) 198 sec  C) 178 sec  D) 20 sec  E) 276 sec
Time taken to meet for the first time at the starting point   = LCM { length of the track / speed of A , length of the track / speed of B}   = LCM { 200/ (36 * 5/18) , 200/ (72 * 5 /18) }   = LCM (20, 10) = 20 sec.   Answer:20 sec
<result>D</result>
A and B go around a circular track of length 200 m on a cycle at speeds of 36 kmph and 72 kmph. After how much time will they meet for the first time at the starting point?