Niharika covers a distance in 30 min , if she drives at a speed of 60 km/h on an average. Find the speed at which she must drive at to reduce the time of the journey by 30%. Pick: A) 84.71 kmph . B) 85.74 kmph . C) 83.71 kmph . D) 85.71 kmph . E) 84.71 kmph .

Rationale: given speed = 60 kmph . it means niharika covered 60 km in 60 min ( 1 hour ) . so , in 30 min he will cover 30 km . 30 % time reduced = 30 - 30 % of 30 = 21 min . thus , niharika needs to cover 30 km in 21 min ( 0.35 hour ) . speed * time = distance . speed * 0.35 = 30 speed = 85.71 kmph . answer : option d
Answer: D