Question

A bus covers half of the total distance with a speed of 30 kmh\(^{-1}\) and other half with a speed of 60 kmh\(^{-1}\). The average speed during the total journey is

• A. 35 kmh\(^{-1}\)
• B. 40 kmh\(^{-1}\)
• C. 45 kmh\(^{-1}\)
• D. 42 kmh\(^{-1}\)
• E. 50 kmh\(^{-1}\)

Hint:

Caution: Do not take the simple arithmetic mean \((30+60)/2 = 45\). This only works if the travel times are equal. For equal distances, always use the harmonic mean.

Answer 1

The Correct Option is B