Question

A van covers the first 30 km in 30 min and the next 30 km in 40 min. Calculate the average speed for the entire journey.

• A. 51.4 km/h
• B. 52.4 km/h
• C. 55.5 km/h
• D. 51.2 km/h

Answer 1

Step 1: Given Data:

Time taken to cover first 30km, $t_1=30min=\frac{30}{60}=\frac{1}{2}hr$

Time taken to cover next 30km, $t_2=40min=\frac{40}{60}=\frac{2}{3}hr$

Step 2: Calculation of average speed:

Total distance covered = $\text{30 km + 30 km = 60 km}$

Total time taken =$\frac{1}{2}+\frac{2}{3}⟹\frac{3+4}{6}=\frac{7}{6}hr$

So, average speed =

$\frac{TotalDistance}{Totaltimetaken}=\frac{60km}{\frac{7}{6}hr}$

$\frac{TotalDistance}{Totaltimetaken}=\frac{60\times 6}{7}$

$\frac{TotalDistance}{Totaltimetaken}=51.4kmh{r}^{-1}$

Thus,

The correct answer is option (a) $51.4kmh{r}^{-1}$