Question

On the River current a canoe traveled 30 km in 3 hours and 20 min, against the current the canoe traveled 28 km in 4 hours. how far will the canoe go in 1.5 hours on the lake?

Answer 1

12 km

Explanation:

Let

x km/h = speed of the canoe on the lake

y km/h = speed of the current

With the current:

Speed = x + y km/h

Distance = 30 km

Time = 3 hours 20 minutes =
`3(1)/(3)` hours

Thus,

`30=3(1)/(3)(x+y)\\ \\30=(10)/(3)(x+y)\\ \\90=10(x+y)\\ \\x+y=9`

Against the current:

Speed = x - y km/h

Distance = 28 km

Time = 4 hours

Thus,

`28=4(x-y)\\ \\x-y=7`

Add these two equations:

`x+y+x-y=9+7\\ \\2x=16\\ \\x=8\ km/h`

On the lake:

Time = 1.5 hours

Speed = 8 km/h

Distance
`=8\cdot 1.5=12\ km`