Answer:
Magnitude of the force exerted on the handle = 66 N
Explanation:
Power is the ratio of work and time.
    [tex]P=\frac{W}{t}\\\\W=Pt=84\times 1.1=92.4J[/tex]
We have work done by rower = 92.4 J
We also have
      Work = Force x Displacement
      92.4 = Force x 1.4
      Force = 66 N
Magnitude of the force exerted on the handle = 66 N