Multiple choice

A car covers one-fourth of the distance at 30 km/h and the remaining distance at 60 km/h. The average speed is:

  1. 40 km/h

  2. 45 km/h

  3. 48 km/h

  4. 50 km/h
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let total distance be 120 km. 1/4 distance = 30 km. Time 1 = 30/30 = 1 hr. Remaining distance = 90 km. Time 2 = 90/60 = 1.5 hr. Total time = 2.5 hr. Average speed = 120 / 2.5 = 48 km/h.

AI explanation

When equal distances are traveled at different speeds, use the harmonic mean formula for average speed: 2xy / (x + y). Plugging in the speeds gives (2 * 30 * 60) / (30 + 60), which equals 3600 / 90. This calculation gives an average speed of 48 km/h.

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