In 15 seconds, the boat swims 100 m. What distance will the boat sail in 1 minute? in 8min?

Given:
t1 = 15 s,
S1 = 100 m,
t2 = 1 min = 60 s,
t3 = 8 min = 480 s.
S2 -?
S3 -?
Decision.
Let’s assume that the boat sails at the same speed every time interval:
V1 = V2 = V3 = V. (1)
By definition of speed:
V = S / t. (2)
V = S1 / t1. (3)
Substitute numerical values in (3):
V = 100/15 = 6.7 (m / s).
From (2) we express S:
S = V * t. (4)
S2 = V * t2. (5)
S3 = V * t3. (6)
Substitute the numerical values in (5), (6):
S2 = 6.7 * 60 = 402 (m).
S3 = 6.7 * 480 = 3216 (m).
Answer: 402 m, 3216 m.