Answer:
Force due to seat must be equal to the Weight of the student
Step-by-step explanation:
As we know that the student is sitting on the seat at rest
So here we can say that at this position the student must be at equilibrium position
so we can write force equation for this position of student
vertically downward the net force is due to his/ her weight which is given as

now this weight of the student is counter balanced by the the normal force due to seat which is in opposite direction
Now for equilibrium position of the object we will have

so the seat will push the student upwards by force which is equal to the weight.