boat speed= 8 m/s
river current= 5 m/s
the resultant speed of the motorboat rounded to the nearest 10.
use pythagorean theorem.
let the unknown be "x".
[tex] {a}^{2} = {b}^{2} + {c}^{2} [/tex]
[tex] {c}^{2} = \sqrt{ {a}^{2} + {b}^{2} } [/tex]
[tex]x = \sqrt{ {8}^{2} + {5}^{2} } [/tex]
[tex]x = \sqrt{64 + 25} [/tex]
[tex]x = 9.4 \: m |s[/tex]
hence, the resultant speed of the motorboat is 9.4 m/s