Multiple choice

A man drives to his office at a speed of 60 km/hr and returns home along the same route at a speed of 30 km/hr. Find the average speed for the total distance.

  1. 50 km/hr

  2. 45 km/hr

  3. 40 km/hr

  4. 55 km/hr

  5. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The average speed for a round trip over the same distance is given by 2xy / (x + y), where x and y are the speeds. Here, 2 * 60 * 30 / (60 + 30) = 3600 / 90 = 40 km/hr.

AI explanation

Since the distance travelled in both directions is the same, use the harmonic mean formula for average speed: 2xy divided by x plus y, where x is the going speed and y is the returning speed. Substituting the given values gives 2 multiplied by 60 multiplied by 30 divided by 60 plus 30. This simplifies to 3600 divided by 90, which equals an average speed of 40 km/hr.

Keep practicing — related questions