If the pressure on the board is doubled, it means that the pressure is now:
P = 2*1.00 Pa = 2.00Pa
Use the following formula for the pressure and solve for the force F:
where A is the area of the board (1.00m^2) and F the force exerted on the area (in this case the weight).
Then, by replacing the values of A and P you obtain:
where you have considered that 1Pa = 1N/m^2.
Hence, the required weight is 2.00N