AP Physics: Electric Potential-Please Help-10 points for best answer?

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A charge +Q is uniformly distributed around a wire ring of radius R. Assume that the electric potential is zero at x = infinity with the origin O of the x-axis at the center of the ring.

a. What is the electric potential at point P (x,0) on the x-axis?
b. Where along the x-axis is the electric potential the greatest? Justify your answer.
c. What is the magnitude and direction of the electric field at point P?
d. Describe the graph of the electric field magnitude as a function of distance along the x-axis.

Note: I have done this problem but i am unsure of my answers. Thanks for any help you can provide.