Multiple choice

David and Emma are participating in a charity walkathon. They both start from the same point and head towards a checkpoint 5 kilometers away. David walks at a constant speed and takes 10 minutes to walk each kilometer. Emma starts her walk 6 minutes after David and walks at a different constant speed. When David reaches the checkpoint, he takes a 5-minute rest before starting to walk back. After walking back 1 kilometer, he meets Emma on her way to the checkpoint. If David's speed is 6 kilometers per hour, how long does it take Emma to walk 1 kilometer?

  1. 12.75 minutes

  2. 10 minutes

  3. 13.75 minutes

  4. 14.75 minutes
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

David's speed = 6 km/h = 0.1 km/min. He takes 10 min/km. David reaches 5km in 50 mins. He rests 5 mins (total 55 mins). He walks back 1km (10 mins), so at 65 mins, he is at 4km from start. Emma starts at 6 mins. Let Emma's speed be v. She reaches 4km at 65 mins. Time taken by Emma = 65 - 6 = 59 mins. Speed = 4km / 59 min. Time for 1km = 59/4 = 14.75 minutes.

Keep practicing — related questions