A point charge of mass 0.210kg, and net charge + 0.340μC hangs at rest at the end

Question:

A point charge of mass 0.210kg, and net charge + 0.340μC hangs at rest at the end of an insulating string above a large sheet of charge. The horizontal sheet of uniform charge creates a uniform vertical electric field in the vicinity of the point charge. The tension in the string is measured to be 5.67N. Calculate the magnitude and direction of the electric field due to the sheet of charge (Fig. 16-67).