The jogging track in a sports complex is 640 m in circumference. Lata and Geeta start from the same point and walk in opposite directions at 4.2 km/hr and 3.8 km/hr respectively. They will meet for the first time in?	Choose the correct choice from the following.
A) 2.9 min
B) 3.9 min
C) 4.2 min
D) 4.8 min
E) 5.6 min

Rationale: clearly , the two will meet when they are 640 m apart . to be ( 4.2 + 3.8 ) = 8.0 km apart , they take 1 hour . that is 60 min . to be 640 m apart , they take ( 640 / 8000 * 60 ) min = 4.8 min . answer : d
Answer: D