Here in crash test the two forces are acting on the dummy in two different directions
As we know that force is a vector quantity so we need to use vector addition laws in order to find the resultant force on it.
So here two forces are given in perpendicular direction with each other so as per vector addition law we need to use Pythagoras theorem to find the resultant of two vectors
so we can say
here given that
now we will plug in all data in the above equation
so it will have net force 4501.9 N which will be reported by sensor