On the AB route, 40 km long, the tourist walked at the same speed for the first 5 hours, and then

| June 1, 2021 | education

On the AB route, 40 km long, the tourist walked at the same speed for the first 5 hours, and then after a 40-minute halt, he reduced the speed by 0.5 km / h and arrived in B, spending 9 hours for the entire journey. How fast did the tourist walk after a halt?

We accept the initial speed of the tourist as x km / h.

In this case, in 5 hours he covered: 5 * x km.

After the tourist reduced his speed by 0.5 km / h, it was: x – 0.5 km / h.

The travel time of the tourist with the new speed was:

9 – 5 – 2/3 h = 3 1/3 h.

So he passed: 3 1/3 * (x – 0.5).

We get the equation:

5 * x + 3 1/3 * x – 1 2/3 = 40.

8 2/3 * x = 40 + 1 2/3.

8 2/3 * x = 41 2/3.

x = 41 2/3/8 1/3 = 41 2/3 * 3/25 = 125/3 * 3/25 = 5 km / h (speed to halt).

x – 0.5 = 5 – 0.5 = 4.5 km / h (speed after a halt).

Answer: 4.5 km / h.



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