Question

A boat took 5 h to travel 60 km up a river, against the current. The return trip took 3 h. Find the speed of the boat in still water and the speed of the current.

Answer 1

Correct answer: V₁ boat = 16 km/h and V₂ current = 4 km/h

Explanation:

If we take speed (velocity) of the boat as V₁ and speed of the current V₂

Let us form equations:

Traveling down the current V₁ + V₂ = 60/3 = 20 km/h

Traveling against the current V₁ - V₂ = 60/5 = 12 km/h

V₁ - V₂ = 12

V₁ + V₂ = 20

If we add up the left and right sides of the equations we get:

2 V₁ = 32 => V₁ = 32/2 = 16 km/h

from the second equation we get:

V₂ = 20 - V₁ = 20 - 16 = 4 km/h

V₂ = 4 km/h

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