Two pedestrians have traveled the same path. The first half of the entire journey went at a speed of 5 km / h

| March 11, 2021 | education

Two pedestrians have traveled the same path. The first half of the entire journey went at a speed of 5 km / h, and the rest of the way – at a speed of 3 km / h. The second pedestrian walked half of the time spent at a speed of 5 km / h, and the rest of the time – at a speed of 3 km / h. Which of them went all the way faster?

Let’s find the average speed of the first pedestrian:

According to the condition of the problem, the first half of the journey he walked at a speed of 5 km / h, and the second at a speed of 3 km / h, that is, the total travel time:

t = S / 2 * 5 + S / 2 * 3 = S / 10 + S / 6 = 8 * S / 15. The average speed will be:

Vav1 = S / t = S / 8 * S / 15 = 15/8 = 1.9 km / h.

Now let’s find the average speed of the second pedestrian:

According to the condition of the problem, half of the time spent he walked at a speed of 5 km / h, and the second half at a speed of 3 km / h, that is, he covered a path equal to:

S = 5 * t / 2 + 3 * t / 2 = 8 * t / 2, hence the average speed of the second pedestrian:

Vav2 = S / t = 8 * t / 2 * t = 4 km / h.

As you can see, the average speed of the second pedestrian is greater than that of the first. This means that the second pedestrian traveled faster.



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