Multiple choice

A car moves for half of its time at $80Km/hr$ and for rest of time $40 Km/hr$. If total distance covered is $60Km,$ the average sped of the car is:

  1. $120Km/hr$
  2. $100Km/hr$
  3. $80Km/hr$
  4. $60Km/hr$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Average speed = Total distance / Total time. Let total time be 2T. Time at 80 km/h is T, time at 40 km/h is T. Distance = 80T + 40T = 120T. Given 120T = 60, so T = 0.5 hours. Total time = 1 hour. Average speed = 60 km / 1 hour = 60 km/h.

AI explanation

Using the formula for average speed when travelling for equal intervals of time, the average speed is simply the arithmetic mean of the two speeds. The average of 80 km/hr and 40 km/hr is (80 + 40) divided by 2. This results in an average speed of 60 km/hr. The total distance given in the problem is consistent with this average speed, confirming the calculation.

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