Multiple choice

A car covers first $2km$ of the total distance of $4km$ with a speed of $30km/h$ and the remaining distance of $2km$ with a speed of $20km/h$. The average speed of the car is:

  1. $24km/h$
  2. $25km/h$
  3. $50km/h$
  4. $26km/h$
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A Correct answer
Explanation

Average speed is total distance divided by total time. Total distance is 4 km. Time for first 2 km is 2/30 = 1/15 hours. Time for second 2 km is 2/20 = 1/10 hours. Total time is 1/15 + 1/10 = 5/30 = 1/6 hours. Average speed = 4 / (1/6) = 24 km/h.

AI explanation

Calculate the total time taken by dividing each segment's distance by its respective speed: (2/30) + (2/20) hours. This gives a total time of (1/15) + (1/10) = (2/30) + (3/30) = 5/30 = 1/6 hours. The total distance is 4 km, so dividing this by the total time yields 4 / (1/6), giving an average speed of 24 km/h.

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