Multiple choice

A train covers the first $5km$ of its journey at a speed of $30km/hr$ and the next $15km$ at a speed of $45km/hr$. What is the average speed of the train?

  1. $35km/hr$
  2. $37.5km/hr$
  3. $39.5km/hr$
  4. $40km/hr$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Average speed is calculated as the total distance divided by the total time taken. The total distance is 5 km + 15 km = 20 km, and the total time is (5/30) + (15/45) = 1/6 + 1/3 = 1/2 hour, resulting in an average speed of 20 / (1/2) = 40 km/hr.

AI explanation

The average speed is calculated by dividing the total distance traveled by the total time taken. The time for the first 5 km is 5/30 hours and the time for the next 15 km is 15/45 hours, resulting in a total time of 1/6 + 1/3 = 1/2 hour. Since the total distance is 5 km + 15 km = 20 km, the average speed is 20 km divided by 0.5 hours, which equals 40 km/hr.

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