The current speed is 2.2 km / h. The boat’s own speed is 15.3 km / h.

The current speed is 2.2 km / h. The boat’s own speed is 15.3 km / h. What path did the boat make if it went downstream for 3 hours, and against 4

1. Let’s designate:

u = 2.2 km / h – river flow speed;
v = 15.3 km / h – speed of the boat in still water;
v1 is the speed of the boat along the river;
v2 is the speed of the boat against the stream of the river;
t1 = 3 h – time downstream;
t2 = 4 h – time upstream.
s1 and s2 – paths upstream and upstream.
2. Speed of the boat v1 and v2:

v1 = v + u;
v2 = v – u.
3. Distance traveled in both directions:

s1 = v1t1 = (v + u) t1;
s2 = v2t2 = (v – u) t2;
s = s1 + s2 = (v + u) t1 + (v – u) t2;
s = (15.3 + 2.2) * 3 + (15.3 – 2.2) * 4;
s = 17.5 * 3 + 13.1 * 4 = 52.5 + 52.4 = 104.9 (km).
Answer: 104.9 km.