Question

A motorboat travels Downstream on a river for 5 hours. The speed of the current is 2 km/h. The river flows into a still Lake and the motorboat continues for two more hours. The distance covered by the boat on the river was 40 km more than the distance that was covered on the lake. What is the speed of the motorboat in still water?

Answer 1

Answer:

I think it is 10 km/hr

Step-by-step explanation:

5 hrs = 40 more with 2 km/hr current

2 hrs= less 40 no current

40-2x5=30

30 without current for three hours

30/3=10 km/hr no current

CHECK

10x2=20

10x5=50+2x5=60

Answer 2

The speed of the motorboat in still water is 10 km/hr

A motorboat travels downstream on a river for 5 hours.      

 

The speed of the current = 2 km/h

The river flows into a still lake and the motorboat continues for two more hours.

The distance covered by the boat on the river was 40 km more than the distance that was covered on the lake.

We have to determine the speed of the motorboat in still water

Let the speed of motorboat in still water = m km/h

Given that

The speed of river current = 2 km/hr

The river runs into a still lake

The motorboat continues to travel for 2  more hours

The distance traveled by the motorboat in two more hours in the lake  = 2m km

The distance covered by the boat in the river = (40 +2m)   km

Net speed of the boat in the river = (m +2 ) km/hr

Let t  be the time spent by motorboat into the river.

$\rm Time = \dfrac{Distance}{Speed}$

$\rm t = \dfrac{40+2m }{m +2}..........(1)$

Given that the motorboat travels downstream of the river for 5 hrs

so on putting t = 5 in equation (1).

$\rm 5 = \dfrac{40 +2m }{m+2}\\\\5m +10 = 40 +2m\\5m -2m = 40-10\\3m = 30\\m = 10 km/h$

So the speed of the motorboat in still water is 10 km/hr

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https://brainly.com/question/12846122