physics help?

[Jackie]

A very small 8.8 g plastic ball (carrying a
charge) is suspended by a 10.9 cm string in a
uniform electric field of 39000 N/C that points to the right. the ball moves to the right.

Is the ball's charge positive, negative, or is it impossible to tell??

[Rothenstein B]

a positive electric charge located in an electric field is acted upon by a force which shows in the direction of the field and so it will move in that direction. so the answer to your question is that the involved electric charge is POSITIVE,