Express your answer to two significant figures and include the appropriate units.
The impulse is the area under that force curve (the integral of F dt, if you’ve had Calc 1).
The ramps up and down each have (1/2)bh = (1/2)(2 s)(Fmax) areas, for a combined area 2s*Fmax.
The middle rectangle has area bh = 4s*Fmax.
You need the total (6 s)*(Fmax) to equal 7.8 Ns, so
Fmax = (7.8 Ns) / (6 s) = 1.3 N