Question

Vincent sets off from his home on a 70 km journey to his friend's house. He travels the first 40 km of his journey at an average speed of 40 km/h and the remaining at an average speed of 60 km/h. Calculate the average speed for his entire journey.

Answer 1

Answer:

50km/h.

Step-by-step explanation:

$70 km \: {5}^{2}$

Answer 2

Answer:

$46\frac{2}{3}\:\mathrm{km/h}$

Step-by-step explanation:

Average speed can be given by:

$S=\frac{d}{t}$, where $d$ is the total distance travelled and $t$ is the time it takes to travel said distance.

Vincent total travels $70$ kilometers in a total time of:

$\frac{40}{40}+\frac{30}{60}=1.5\:\mathrm{hours}$.

Therefore, his average speed during the entire trip is:

$S=\frac{70}{1.5}=\fbox{ 46\frac{2}{3}\:\mathrm{km/h} }$.