### A man covers half of his journey at 6 km/h and the remaining half at 3 km/h. His average speed is

A. A. 9 km/h B. 4.5 km/h C. 4 km/h D. 3 km/h Answer: Option C
Average Speed $\begin{array}{l} =\frac{2 x y}{x+y} \\ =\frac{2 \times 6 \times 3}{6+3} \\ =\frac{36}{9} \\ =4 \mathrm{kmph} \end{array}$