Two persons start running simultaneously around a circular track of length 100 m from the same point at speeds of 10 km/hr and 20 km/hr. When will they meet for the first time any where on the track if they are moving in opposite directions ? Choose the most appropriate option:
A) 20 sec B) 12 sec C) 19 sec D) 32 sec E) 28 sec
Explanation:   Time taken to meet for the first time anywhere on the track   = length of the track / relative speed   = 100 / (10 + 20)5/18 = 100 x 18 / 30 x 5 = 12 seconds.   Answer: 12 sec
<result>B</result>
Two persons start running simultaneously around a circular track of length 100 m from the same point at speeds of 10 km/hr and 20 km/hr. When will they meet for the first time any where on the track if they are moving in opposite directions ?