Multiple choice

Sarah rides her bike around a triangular track, with each side measuring 5 kilometres. She covers the first side at a speed of 40 km/h and increases her speed by 5 km/h on each subsequent side. If she completes the entire triangular route, what is her average speed for the journey?

  1. 39.45 km/h

  2. 47.74 km/h

  3. 44.63 km/h

  4. 52.25 km/h

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

Total distance is 15 km. Time for each side: t1 = 5/40 = 0.125 h, t2 = 5/45 = 0.111 h, t3 = 5/50 = 0.1 h. Total time = 0.3361 h. Average speed = 15 / 0.3361 = 44.63 km/h.

AI explanation

The average speed for the entire journey is calculated using the formula total distance divided by total time. The total distance is 15 kilometers, and the total time is the sum of the times for each side, which are 5 divided by 40, 5 divided by 45, and 5 divided by 50 hours respectively. This gives a total time of 0.125 plus 0.1111 plus 0.1, resulting in approximately 0.3361 hours. Dividing 15 kilometers by 0.3361 hours gives an average speed of 44.63 kilometers per hour.

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