A person walks at a speed of 4 km/hr and runs at a speed of 8 km/hr. How many hours will the person require to cover a distance of 4 km, if the person completes half of the distance by walking and the other half by running?
Choose the correct choice
A) 0.25 B) 0.5 C) 0.75 D) 1 E) 1.25

Rationale: "time = 2 / 4 + 2 / 8 = 6 / 8 = 0.75 hours the answer is c ."
Answer: C