A boat moves at 10.8 m/s relative to the water. If the boat is in a river where the current is 2.00 m/s, how long does it take the boat to make a complete round trip of 1 100 m upstream followed by a 1 100-m trip downstream?

336 s

250 s

172 s

297 s

211 s

Option E is the correct answer.

Explanation:

Velocity of boat = 10.8 m/s

Velocity of river = 2 m/s

Relative velocity upstream = 10.8 - 2 = 8.8 m/s

Displacement = Velocity x Time

1100 = 8.8 x t₁

Time in upstream, t₁ = 125 s

Relative velocity downstream = 10.8 + 2 = 12.8 m/s

Displacement = Velocity x Time

1100 = 12.8 x t₂

Time in downstream, t₂ = 86 s

Total time = t₁ + t₂ = 125 + 86 = 211 s

Option E is the correct answer.