Multiple choice

A car travels a certain distance at a speed of 70 km/h and comes back at a speed of 30 km/h. Find the average speed for the whole journey.

  1. 42 km/hr

  2. 50 km/hr

  3. 34 km/hr

  4. 58 km/hr
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Average speed = (2 * v1 * v2) / (v1 + v2) = (2 * 70 * 30) / (70 + 30) = 4200 / 100 = 42 km/h.

AI explanation

Using the harmonic mean formula for equal distances, the average speed equals twice the product of the speeds divided by their sum, which is 2 multiplied by 70 multiplied by 30 and then divided by the sum of 70 and 30. This simplifies to 4200 divided by 100, giving an average speed of 42 km/hr.

Keep practicing — related questions