### A man travels equal distances of his journey at 40, 30 and 15 km/h. respectively. Find his average speed for whole journey.

**A.** 24

**B.** 25

**C.** 27

**D.** 28

## Show Answer

###
Answer-A

Solution-

__Solution(By Apex Team)__

$\begin{array}{l}\text{Required average speed,}\\
=\Large\frac{(3 \times 40 \times 30 \times 15)}{(40 \times 30)+(40 \times 15)+(30 \times 15)} \\
=24 \mathrm{~km} / \mathrm{hr}
\end{array}$

**$\begin{array}{l}\text{Time taken to traveled}\\ =\Large\frac{1}{3}\end{array}$ distance of journey with speed 40 kmph, $\begin{array}{l}=\Large\frac{\frac{1}{3}}{40}=\frac{1}{120}\end{array}$ $\begin{array}{l}\text{Time taken to traveled}\\ =\Large\frac{1}{3}\end{array}$ distance of journey with speed 30 kmph, $\begin{array}{l}=\Large\frac{\frac{1}{3}}{30}=\frac{1}{90}\end{array}$ $\begin{array}{l}\text{Time taken to traveled}\\ =\Large\frac{1}{3}\end{array}$ distance of journey with speed 15 kmph, $\begin{array}{l}=\Large\frac{\frac{1}{3}}{15}=\frac{1}{45}\\ \text{ Total time taken }\\ =\Large\frac{1}{120}+\frac{1}{90}+\frac{1}{45}\\ =\Large\frac{45}{1080}\\ \text{Average speed}\\ =\left(\Large\frac{\text{Total distance travelled}}{\text{Total time taken}}\right)\\ =\Large\frac{1}{\frac{45}{1080}}\\ =24\mathrm{kmph}\end{array}$**