Multiple choice

$A$ car travels a distance of $45$ km at a speed of $15$ km/hr. It covers the next $50$ km of its journey at the speed of $25$ km/hr and the last $25$ km of its journey at the speed of $15$ km/hr. What is the average speed of the car?

  1. $40$ km/hr
  2. $24$ km/hr
  3. $15$ km/hr
  4. $18$ km/hr
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Average speed = Total distance / Total time. Total distance = 45 + 50 + 25 = 120 km. Total time = 45/15 + 50/25 + 25/15 = 3 + 2 + 1.66 = 6.66 hours. 120 / 6.66 = 18 km/hr.

AI explanation

Total distance equals 45 km plus 50 km plus 25 km, giving 120 km. Using the formula time equals distance divided by speed, the times for the three parts are 3 hours, 2 hours, and 5/3 hours respectively, making the total time 26/3 hours. The average speed is 120 divided by 26/3, resulting in 18 km/hr.

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