I need to make up my work and only can answer it

Which equations represents circles that have a diameter of 12 units and a center that lies on the y-axis? check all that apply

The lengths of nails produced in a factory are normally distributed with a mean of 4.91 centimeters and a standard deviation of 0.05 centimeters. find the two lengths that separate the top 4% and the bottom 4%. these lengths could serve as limits used to identify which nails should be rejected. round your answer to the nearest hundredth, if necessary.

Factor this polynomial completely x^2-64