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Let s be the speed of the ship, and c be the speed of the current. 

We know that distance equals speed multiplied by the time. 

With the current
     [tex]\left(s+c\right)\left(4\:hours\right)=420\:km[/tex]
     or
     [tex]s+c=105[/tex]
This is our first equation.

Now, against the current, we have
     [tex]\left(s-c\right)\left(6\right)=420[/tex]
     or
     [tex]s-c=70[/tex]
This is our second equation. 

We solve the equations simultaneously, by adding them together
     [tex]2s-0c=175[/tex]

     [tex]s=87.5\:km/hr[/tex]

Substitute s=87.5 to the first equation to solve for c.
     [tex]87.5+c=105[/tex]

     [tex]c=17.5\:km/hr[/tex]

The speed of the ship is 87.5 km/hr and the speed of the current is 17.5 km/hr. 
     

The speed of the ship is 87.5 km/hr and the speed of the current is 17.5 km/hr.

What is the speed of the current?

The actual propagation speed depends on the size of the wire and electrical parameters such as its inductance, but it is normally approximately 90% of the speed of light—about 270,000 km/s.

Let x be the speed of the ship, and y be the speed of the current.

It takes a ship 4 hours to cover 420 km with the current and 6 hours against the current.

[tex]\rm (x+y)4=420\\\\x+y=\dfrac{420}{4}\\\\x+y=105[/tex]

And the second equation is;

[tex]\rm (x-y)6=420\\\\x-y=\dfrac{420}{6}\\\\x-y=70[/tex]

Adding both the equation

[tex]\rm x+y+x-y=105+70\\\\2x=175\\\\x=\dfrac{175}{2}\\\\x=87.5[/tex]

Substitute the value of x in equation 1

[tex]\rm x+y=105\\\\87.5 +y=105\\\\y=105-87.5 \\\\y= 17.5[/tex]

Hence, the speed of the ship is 87.5 km/hr and the speed of the current is 17.5 km/hr.

   

To know more about the speed of current click the link given below.

https://brainly.com/question/26701593

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