Sachin covers half of his journey at 12 km/h and the remaining half at 3 km/h. His average speed is:
4.8 km/h
When equal distances are covered at two different speeds, the average speed is given by the harmonic mean formula \(\text{Average speed} = \frac{2v_1v_2}{v_1+v_2}\).
Here \(v_1 = 12\) km/h and \(v_2 = 3\) km/h, so the average speed is \(\frac{2 \times 12 \times 3}{12+3} = \frac{72}{15}\).
Simplifying, \(\frac{72}{15} = 4.8\).
Hence, the answer is 4.8 km/h.
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Important Questions from Average Speed
A person covers a certain distance at the speed of 60 kmph and returns to the starting point at a speed of 40 kmph . Find the average speed (in km/hour) of the person for the whole journey.
A train runs at a speed of 28 kmph for 4 hours and 30 kmph for 5 hours and the remaining 40 kms in one hour. What is the average speed per hour?
Kapil travels for 4.5 hours at a speed of 50 km / h and 7.5 hours at a speed of 70 km / h. At the end of it, he finds that he covered only 6/7 of the total distance. At what average speed should he travel so that the remaining distance traveled in 5 hours?
An express train travelled at an average speed of 100 km/hr, stopping for 3 minutes after every 75 km. How long it take to reach its destination 600 km from the starting point?
A car has to cover 125 kms in 5 hours. What will be the average speed of the car if it has covered 90 kms in the first 3 hours?
