Respuesta :
Speed in still water= [tex]\sqrt{43}[/tex]miles
Let take the speed in still water be x and the speed of current in the river be y.
The speed of the current in a river= 5 miles
Let the distance be s which is 1.2 miles.
The time(t) difference is 40 minutes.
We have an equation,
[tex]\frac{s}{x-y}[/tex] - [tex]\frac{s}{x+y}[/tex] = t
[tex]\frac{1.2}{x - 5}[/tex] - [tex]\frac{1.2}{x + 5}[/tex] = [tex]\frac{40}{60}[/tex]
1.2 × 60(2 × 5) = 40([tex]x^{2}[/tex] - 25)
x =[tex]\sqrt{43}[/tex]
Therefore the speed in still water is [tex]\sqrt{43}[/tex].
To know more about the boat and river solution refer to the link given below:
https://brainly.com/question/15394794
