Multiple choice

A car covers half the distance at a speed of $50 {km}/{h}$ and the other half at $40 {km}/{h}$. Find the average speed of the car.

  1. $74.44 {km}/{h}$
  2. $44.44 {km}/{h}$
  3. $54.44 {km}/{h}$
  4. $64.44 {km}/{h}$
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B Correct answer
Explanation

Average speed for equal distances is 2xy / (x + y). Average speed = 2 * 50 * 40 / (50 + 40) = 4000 / 90 = 44.44 km/h.

AI explanation

When equal distances are traveled at two different speeds, the average speed is given by the harmonic mean formula: twice the product of the speeds divided by their sum. Substituting the given speeds into the formula gives twice 50 multiplied by 40, divided by the sum of 50 and 40. This calculates to 4000 divided by 90, which equals 44.44 km/h.

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