A, B, K start from the same place and travel in the same direction at speeds of 30 km/hr, 40 km/hr, 160 km/hr respectively. B starts two hours after A. If B and K overtake A at the same instant, how many hours after A did K start?	Choose the correct choice from the following:  A) 5.0  B) 5.5  C) 6.0  D) 6.5  E) 7.0
In 2 hours, A travels 60 km.   B can catch A at a rate of 10 km/hr, so B catches A 6 hours after B starts.   So A and B both travel a distance of 240 km.   C needs 1.5 hours to travel 240 km, so C leaves 6.5 hours after A.   The answer is 6.5.
<result>D</result>
A, B, K start from the same place and travel in the same direction at speeds of 30 km/hr, 40 km/hr, 160 km/hr respectively. B starts two hours after A. If B and K overtake A at the same instant, how many hours after A did K start?