Answer:
24.8 mph
Explanation:
as we know if one sailed north and another east, the angle with respect to the port will be 90 degrees
This means that the distance of each ship to the pier can be the legs of a rectangular triangle
The distance of a ship from the other would be represented by the hypotenuse
h: Hipotenuse
c1: leg 1
c2: leg 2
By Pythagoras we know that the hypotenuse is equal to
h = √(c1^2 + c^2)
if we replace with the values we have left
h = √(18^2 + 17^2)
h = √(324 + 289)
h = √613
h = 24.758
we round a decimal place
h = 24.8