A person travels from P to Q a speed of 60 km/hr and returns by increasing his speed by 20%. What is his average speed for both the trips?  Choose one:  A) 33  B) 77  C) 48  D) 66  E) 21

Rationale: "speed on return trip = 120 % of 60 = 72 km / hr . average speed of trip = 60 + 72 / 2 = 132 / 2 = 66 km / hr answer : d"
Answer: D