A car travels from point A to point B. The average speed of the car is 60 km/hr and it travels the first half of the trip at a speed of 75 km/hr. What is the speed of the car in the second half of the trip?	Pick one.
A) 40
B) 45
C) 48
D) 50
E) 55

Rationale: let d be the distance and let v be the speed in the second half . the total time = t 1 + t 2 d / 60 = d / 150 + ( d / 2 ) / v d / 100 = d / 2 v and so v = 50 km / hr the answer is d .
Answer: D