Multiple choice

Every morning, Priya rides her bicycle from her apartment in Oakwood to her office downtown. One day, she decides to double her usual speed. By doing so, she notices that she arrives at her office 45 minutes earlier than usual. If her usual speed is 6 km/h, what is the distance, in kilometres, between Priya's apartment and her office?

  1. 6

  2. 8

  3. 9

  4. 10

  5. 12
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let d be the distance and v be the speed (6 km/h). Time taken is d/6. Doubling speed to 12 km/h, time taken is d/12. The difference is 45 minutes (0.75 hours). So, d/6 - d/12 = 0.75, which simplifies to d/12 = 0.75, so d = 9 km.

AI explanation

Let the usual time taken be t hours. Using the formula time equals distance divided by speed, we write t equals distance divided by 6. At the doubled speed of 12 km/h, the time taken equals distance divided by 12. The difference in time is 45 minutes, which is 0.75 hours, so distance divided by 6 minus distance divided by 12 equals 0.75. Solving this equation gives distance divided by 12 equals 0.75, which means the distance is 9 kilometres.

Keep practicing — related questions