1/3 of the time the tourist walked at a speed of 3 km / h, and the rest of the time – at a speed

1/3 of the time the tourist walked at a speed of 3 km / h, and the rest of the time – at a speed of 6 km / h. Find the average speed of the tourist.

Given:

v1 = 3 km / h – the tourist’s speed for the time interval t1;

t1 = 1/3 * t – time interval;

v2 = 6 km / h – the tourist’s speed for the time interval t2;

t2 = 2/3 * t – time interval;

t is the total travel time of the tourist.

It is required to determine the average speed of the tourist v.

Average speed is determined by the formula:

v = S total / t = (v1 * t1 + v2 * t2) / t = (v1 * t / 3 + 2 * v2 * t / 3) / t =

= (v1 + 2 * v2) / 3 = (3 + 2 * 6) / 3 = (3 + 12) / 3 = 15/3 = 5 km / h.

Answer: the average speed of a tourist is 5 kilometers per hour.